Method of forming a photoresist pattern using an anti-reflective

ABSTRACT

A method of determining an optimum condition of an anti-reflective layer upon forming a resist pattern by exposure with a monochromatic light, forms the anti-reflective layer with these conditions and forms a resist pattern using a novel anti-reflective layer. The method comprises (I) forming an equi-contour line for the amount of absorbed light regarding a photoresist of an optional film thickness using the optical condition of the anti-reflective layer as a parameter, (II) conducting the same procedure as in (I) above for a plurality of resist film thicknesses, (III) finding a common region for the amount of absorbed light with respect to each of the traces obtained, thereby determining the optical condition for the anti-reflective layer, (IV) applying same procedures as described above while changing the condition of the anti-reflective layer, thereby determining the optical condition for the anti-reflective layer, and (V) determining the optimum optical condition such as the kind and the thickness of the anti-reflective layer under a certain condition of the anti-reflective layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 08/175,299 filedDec. 29, 1993, which was a continuation-in-part of U.S. patentapplication Ser. No. 07/998,743, filed Dec. 29, 1992 now abandoned,which has been replaced by a continuation application Ser. No.08/320,119 filed Oct. 11, 1994.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a method of determining conditions for ananti-reflective layer, a method of forming an anti-reflective layer anda method of forming a resist pattern by using a novel anti-reflectivelayer. In particular, it relates to a method of determining a conditionof an anti-reflective layer for defining optical conditions such as athickness and a refractive index condition, for example, reflectionrefractive index and absorption refractive index of an anti-reflectivelayer upon forming a resist pattern by exposing a photoresist on ananti-reflective layer formed on an underlying material by amonochromatic light; a method of forming the anti-reflective layerutilizing the above-mentioned method and a method of forming a resistpattern by using a novel anti-reflective layer. The present inventioncan be utilized suitably, for example, either in a case of setting ananti-reflective layer disposed for preventing the standing wave effectwhen photolithography is used or in a case of forming a resist patternby using an anti-reflective film when photolithography is used uponmanufacturing, for example, electronic materials (such as semiconductordevices).

2. Description of the Prior Art

For instance, in the photolithography, a KrF excimer laser beam (248 nm)is used and is mounted in most advanced steppers (projection exposingmachine) at present (for example, Nikon NSR 1505 EX1, Canon FPA 4500)have a lens of about 0.37 to 0.42 NA. By using the steppers, researchand development have been studied for design rule devices in a sub-haftmicron (0.5 um) region.

In the stepper, a monochromatic light is used as an exposing opticalsource. In a case of exposure by the monochromatic light, it has beengenerally known that a phenomenon referred to as a standing wave effectoccurs. The standing wave is caused by occurrence of a lightinterference in a resist film. That is, it is caused by the interferencebetween an incident light P and a reflection light R from the interfacebetween a resist PR and a substrate S in the film of the resist PR.

As a result, as shown in FIG. 19, the amount of light absorbed in theresist (ordinate in the graph) fluctuates depending on the thickness ofthe resist film (abscissa in the graph). In the present specification,the amount of light absorbed in the resist means an amount of lightabsorbed in the resist itself excluding the amount of light due tosurface reflection, absorption by a metal if it is present in theresist, or light outgoing from the resist. The amount of the absorbedlight constitutes an energy for causing light reaction to the resist.

As can be seen from the comparison between FIG. 20 and FIG. 21, theextent of the fluctuation for the amount of the absorbed light alsodiffers based on the kind of underlying substrates. In FIGS. 19, 20 and21, XP 8843 (manufactured by Shipley Co.) is used in each of the casesand Si, Al-Si and W-Si are used as the underlying material in respectivecases. That is, fluctuation for the amount of the absorbed light isdetermined by a complex swing reflectivity (R) (in which (R) representsthat it is a vector amount having a real part and an imaginary part)considering multiple interference determined by optical constants (n, k)of the underlying material (substrate) and optical constants (n, k) ofthe resist.

In addition, in the actual device, as schematically shown in FIG. 22,unevenness is always present on the surface of a substrate. Forinstance, protrusions In, such as poly-Si, are present. Therefore, whenthe resist PR is coated, the thickness of the resist film varies betweenupper and lower portions of the step. That is, the thickness dPR2 of theresist film on the protrusion In is smaller than the thickness dPR1 ofthe resist film in other portions than the above. As has been describedpreviously, the standing wave effect differs depending on the thicknessof the resist film and, accordingly, fluctuation for the amount of thelight absorbed in the resist changes respectively undergoing the effectof the standing wave effect. As a result, the dimension of the resistpattern obtained after exposure and development differs between theupper and the lower portions of the step.

Influence of the standing wave effect on the dimension of the patternbecomes more remarkable as the pattern is finer in a case of using astepper of an identical wavelength and an identical number of aperture.FIGS. 23-25 show the influence of the standing wave effect on everypattern dimension in a case of using Nikon NSR 1505 EX1 as a stepper(exposure light used: λ=248 nm, KrF excimer, NA=0.42) and using XP 8843as a resist (chemically amplified type resist, a polyvinylphenol typeresist containing optical acid generating agent, manufactured by ShipleyMicroelectronics Co.). It is apparent that the standing wave effectbecomes remarkable as the pattern becomes finer (refer also to thescattering of critical dimension shift at 0.5 um, 0.4 um and 0.35 umline-and-space patterns shown by "open circles" in the drawings).

The above-mentioned trend is a phenomenon observed in common with all ofresists.

The dimensional accuracy of a resist pattern in a photolithographic stepupon manufacturing a device such as a semiconductor device is generally±5%, although it is considered that an accuracy coarser than ±5% intotal may be practically tolerable. However, if occurrence of scatteringdue to the other factors such as focus is also taken into consideration,it is desirable that the pattern accuracy upon a resist exposure iswithin ±5%. For attaining the dimensional accuracy of ±5%, it isessential to reduce the standing wave effect.

FIG. 26 shows a dimensional variation of the resist pattern relative tothe fluctuation (ordinate) for the amount of absorbed light in theresist film (abscissa). As can be seen from FIG. 26, fluctuation for theamount of absorbed light in the resist film has to be within a range ofless than 6% in order to manufacture, for example, a rule device of 0.35um.

For satisfying the above-mentioned requirement, several studies havebeen made on the anti-reflective technique in each of the fields.However, although the type of material for the underlying material andthe resist to be used are known, it is not always easy to determine asto what are the conditions for the anti-reflective layer that can attainan anti-reflective effect suitable to such a case.

For instance, in the formation of a pattern on a gate structure (forexample, on a W-Si film) for which an anti-reflective layer isconsidered indispensable, it has not yet been determined what are theconditions for the anti-reflective layer that will reduce fluctuationfor the amount of the absorbed light in the resist film, for example toa range of less than 6%. Naturally, no effective anti-reflective layermaterial to be used for such W-Si has yet been found.

For the structure using the W-Si material as the gate, a pattern has nowbeen formed at present, for example, by means of a multi-layer resistmethod or dye-incorporated resist. Accordingly, it is consideredessential to establish anti-reflective technique on W-Si as soon aspossible.

In such a case, if there is a means capable of determining comprehensiveconditions and concrete conditions regarding an anti-reflective layerfor forming a stable fine pattern on an optional underlying material(substrate) using an exposure optical source of an optionalmonochromatic light it can be found for the condition of theanti-reflective layer to be formed, for example, on W-Si. However, nosuch means has yet been proposed.

OBJECT OF THE INVENTION

In view of the foregoing situations, it is an object of the presentinvention to provide a method for determining a condition for ananti-reflective layer which is capable of being used in a case offorming a resist pattern on an optional underlying material (substrate)by using an exposure optical source of an optional monochromatic light,so that a stable resist pattern can be formed satisfactorily even if theresist pattern is fine.

Another object of the present invention is to provide a method offorming an anti-reflective layer by the condition described above.

A further object of the present invention is to provide a method offorming a resist pattern by developing a novel anti-reflective layer andusing such an anti-reflective layer.

SUMMARY OF THE INVENTION

The foregoing object can be attained in accordance with the first aspectof the present invention by a method of determining a condition for ananti-reflective layer upon forming a resist pattern by exposing aphotoresist on the anti-reflective layer formed on an underlyingmaterial by a monochromatic light, wherein the film thickness and theoptical condition of the anti-reflective layer are determined by thefollowing means or steps, which comprises:

(I) determining an equi-contour line for the amount of absorbed light ina photoresist of an optionally determined film thickness using theoptical condition for the anti-reflective layer as a parameter;

(II) determining equi-contour lines for the amount of absorbed light fora plurality of different film thicknesses in the same manner as in (I)above;

(III) finding a common region for the amount of the absorbed light foreach of the equi-contour lines obtained in (II) above and setting theoptical condition defined by the common region as an optical conditionfor the anti-reflective layer in the condition defined initially in (I)above;

(IV) determining the optical condition for the anti-reflective layer byconducting the same procedures as described above while changing thecondition for the anti-reflective film; and

(V) finding the optimum optical condition for the anti-reflective layerin the condition for the anti-reflective layer according to (IV) above.

The foregoing object can be attained in accordance with the secondaspect of the present invention by a method of forming ananti-reflective layer upon forming a photoresist pattern by exposing aphotoresist on the anti-reflective layer formed on an underlyingmaterial by a monochromatic light, wherein the anti-reflective layer isformed by using a substance adaptable to the condition for therefractive index based on the optimum refractive index condition for theanti-reflective layer determined by the means (I)-(V) as defined in thefirst aspect.

The foregoing object can be attained in accordance with the third aspectof the present invention by a method of forming a resist pattern whichcomprises forming an anti-reflective layer with silicon carbide on anunderlying high melting metal silicide material and forming aphotoresist on the anti-reflective layer.

The foregoing object can be attained in accordance with the fourthaspect of the present invention by a method of forming a resist patternby forming an anti-reflective layer on an underlying metal seriesmaterial and forming a photoresist on the anti-reflective layer therebyforming a resist pattern, wherein the anti-reflective film is formedwith an organic or inorganic substance under the conditions of the filmthickness and the optical condition determined by the following means orsteps, which comprises:

(I) determining an equi-contour line for the amount of absorbed light ina photoresist of an optionally determined film thickness using theoptical condition for the anti-reflective layer as a parameter;

(II) determining equi-contour lines for the amount of absorbed light fora plurality of different film thicknesses in the same manner as in (I)above;

(III) finding a common region for the amount of the absorbed light foreach of the equi-contour lines obtained in (II) above and setting theoptical condition defined by the common region as an optical conditionfor the anti-reflective layer in the condition defined initially in (I)above;

(IV) determining the optical condition for the anti-reflective layer byconducting the same procedures as described above while changing thecondition for the anti-reflective film; and

(V) finding the optimum optical condition for the anti-reflective layerin the condition for the anti-reflective layer according to (IV) above.

The foregoing object can be attained in accordance with the fifth aspectof the present invention by a method of forming a resist pattern whichcomprises forming an anti-reflective layer on an underlying metal seriesmaterial with silicon carbide or silicon oxide and forming a photoresiston the anti-reflective layer, thereby forming a resist pattern.

The foregoing object can be attained in accordance with the sixth aspectof the present invention by a method of forming an anti-reflective layeron an underlying inorganic material (including metal material andsilicon material) and forming a resist pattern on the anti-reflectivelayer thereby forming the resist pattern, wherein the anti-reflectivelayer is formed with an organic or inorganic substance satisfying thefilm thickness and the optical condition determined by the followingsteps or means, which comprises:

(I) determining an equi-contour line for the amount of absorbed light ina photoresist of an optionally determined film thickness using theoptical condition for the anti-reflective layer as a parameter;

(II) determining equi-contour lines for the amount of absorbed light fora plurality of different film thicknesses in the same manner as in (I)above;

(III) finding a common region for the amount of the absorbed light foreach of the equi-contour lines obtained in (II) above and setting theoptical condition defined by the common region as an optical conditionfor the anti-reflective layer in the condition defined initially in (I)above;

(IV) determining the optical condition for the anti-reflective layer byconducting the same procedures as described above while changing thecondition for the anti-reflective film; and

(V) finding the optimum optical condition for the anti-reflective layerin the condition for the anti-reflective layer according to (IV) above.

The foregoing object can be attained in accordance with the seventhaspect of the present invention by a method of forming a resist patternwhich comprises forming an anti-reflective layer with silicon carbide orsilicon oxide on an underlying silicon material and forming aphotoresist on the anti-reflective film, thereby forming a resistpattern.

The foregoing object can be attained in accordance with the eighthaspect of the present invention by a method of forming a resist patternas defined by the fourth aspect, wherein an anti-reflective layer isformed on an underlying metal material by using an organic or inorganicsubstance having a value within ±0.6 for the reflection refraction indexn and a value within ±0.2 for the absorption refractive index k andforming a photoresist on the anti-reflective layer, thereby forming theresist pattern.

The foregoing object can be attained in accordance with the ninth aspectof the present invention by a method of forming a resist pattern,wherein an SiO₂ film having reflection refractive index n=2.4±0.6 andabsorptive refraction index k=0.7±0.2 is used as an anti-reflectivelayer on an underlying metal material.

The foregoing object can be attained in accordance with the tenth aspectof the present invention by a method of forming a resist pattern,wherein a Si_(x) O_(y) N_(z) film or a Si_(x) N_(y) film havingreflection refractive index n=2.4±0.6 and absorptive refractive indexk=0.7±0.2 is used as an anti-reflective layer on the underlying metalmaterial.

The foregoing object can be attained in accordance with the 11th aspectof the present invention by a method of forming a resist pattern asdefined by any one of the eighth to tenth aspects, wherein theunderlying metal material comprises a high melting metal silicide.

The foregoing object can be attained in accordance with the 12th aspectof the present invention by a method of forming a resist pattern, inwhich a Si_(x) O_(y) N_(z) film is formed as an anti-reflective layer onthe underlying metal material thereby forming a resist pattern.

The foregoing object can be attained in accordance with the 13th aspectof the present invention by a method of forming a resist pattern asdefined by the 12th aspect, wherein the metal material is aluminumseries material.

The foregoing object can be attained in accordance with the 14th aspectof the present invention by a method of forming a resist pattern inwhich a Si_(x) O_(y) N_(z) or Si_(x) N_(y) film as an anti-reflectivelayer is formed on an underlying silicon series material thereby forminga resist pattern.

The foregoing object can be attained in accordance with the 15th aspectof the present invention by a method of forming a resist pattern asdefined by the 14th aspect, wherein the silicon material comprises anyone of single crystal silicon, polycrystalline silicon, amorphoussilicon and doped poly-silicon.

The first aspect of the present invention comprises, as shown in FIG. 1:

(I) determining an equi-contour line for the amount of absorbed light ina photoresist of an optionally determined film thickness using theoptical condition for the anti-reflective layer as a parameter;

(II) determining equi-contour lines for the amount of absorbed light fora plurality of different film thicknesses in the same manner as in (I)above;

(III) finding a common region for the amount of the absorbed light foreach of the equi-contour lines obtained in (II) above and setting theoptical condition defined by the common region as an optical conditionfor the anti-reflective layer in the condition defined initially in (I)above;

(IV) determining the optical condition for the anti-reflective layer byconducting the same procedures as described above while changing thecondition for the anti-reflective film; and

(V) finding the optimum optical condition for the anti-reflective layerin the condition for the anti-reflective layer according to (IV) above.

An optimum condition for the anti-reflective layer is obtained inaccordance with the foregoing constitution and a substance adaptable tothe condition that is capable of satisfying or substantially satisfyingsuch a condition is selected thereby enabling to form an effectiveanti-reflective layer.

For instance, each of refractive indices n, k at each of specificwavelengths (exposure wavelength) is determined by a means such as aspectroscopic ellipsometer and a substance having such refractiveindices n, k is searched from existent substances as the anti-reflectivematerial, or a substance for such a condition can be synthesized toserve for the anti-reflective material.

Description will then be made to a methodology of determining acomprehensive condition for an anti-reflective layer by using thepresent invention with reference to the drawings.

(1) The thickness of the resist film between maximum values or betweenminimum values of the standing wave effect is given as λ/4n assuming therefractive index of the resist as n_(PR) and the exposure wavelength asλ (refer to FIG. 2).

(2) An anti-reflective layer ARL is assumed between the resist and thesubstrate, with the film thickness as d_(arl) and optical constant asn_(arl), k_(arl).

(3) Taking notice on the film thickness at a certain point in FIG. 2(for instance, a film thickness for maximizing the standing waveeffect), the amount of the absorbed light in the resist film fluctuatesat that point as n_(arl), k_(arl) are changed while the film thicknessd_(arl) of the anti-reflective layer being fixed. The varying trace,that is, the equi-contour lines for the amount of absorbed light isdetermined as shown in FIG. 3. The procedures described above correspondto step (I) in accordance with the present invention.

(4) When the procedure (3) is applied repeatingly to four points each atλ/8n_(PR) interval with reference to other different film thicknessd_(pr) of the resist, at least, film thickness maximizing or minimizingthe standing wave effect, FIG. 4 to FIG. 6 corresponding to FIG. 3 areobtained (in FIGS. 3-6, the thickness of the anti-reflective layer isdefined as 20 nm and the thickness of the resist layer is defined as 985nm, 1000 nm, 1018 nm and 1035 nm, respectively). This corresponds tostep (II).

(5) The common region for each of graphs in FIG. 3 to FIG. 6 shows aregion in which the amount of absorption light in the resist film doesnot fluctuate even if the resist film thickness varies. That is, thecommon region described above is a region having a highestanti-reflective effect for minimizing the standing wave effect.Accordingly, a search is made for such a common region. The commonregion can be found conveniently, for example, by overlapping each ofthe graphs to determine the common region (the common region may, ofcourse, be retrieved by a computer). This corresponds to step (III).

(6) Procedures (3), (4) and (5) are repeated while continuously varyingthe film thickness d of the anti-reflective layer. For instance,assuming that the procedure was conducted, for example, at d=20 nm up to(5), then the above-mentioned procedures are repeated while varying d.This can specify the condition for the film thickness d_(arl) of theanti-reflective layer minimizing the standing wave effect and acondition for the optical constant n_(arl), k_(arl). This corresponds tostep (IV).

(7) The kind of the film that satisfies the condition to be met by theanti-reflective layer specified in (6) above (film thickness, opticalconstant) is found by measuring the optical constant of each kind of thefilms by the exposure light. This corresponds to step (V).

This methodology is applicable, in principle, to all of the wavelengthand the kind of the underlying material (substrate). Further, ananti-reflective layer of an optimum condition can be formed inaccordance with the condition obtained in (7) above and with thesubstance capable of satisfying the condition (corresponding to FIG. 1(VI)).

By using the method in accordance with the present invention, theanti-reflective layer as an effective means for forming a stable finepattern on an optional underlying material (substrate) by using astepper having an optical source of an optional monochromatic light canbe easily designed.

The present invention can be utilized for finding a condition of anorganic or inorganic film for forming an anti-reflective layer used forforming a stable resist pattern on a W-Si film by using a KrF excimerlaser. In this case, a substance having n, k condition shown in FIGS. 14and 15 to be described later can be used. In this case, it is desirableto use such an organic or inorganic layer having a tolerable range foreach of n, k values in FIGS. 14, 15, i.e., ±0.2 for n and ±0.05 for k.As for the anti-reflective layer, it is preferred to use SiC havingn=3.16±0.2, k=0.24±0.05 at a film thickness of 50±10 nm. SiCconstituting the anti-reflective layer can be formed by sputtering orCVD. SiC can also be etched by RIE using CF₄, CHF₃, C₂ F₆ e, C₃ F₈, SF₆or NF₃ series gas as an etchant and by adding Ar to thereby improveionic property.

The third through tenth aspects of the present invention can be attainedby conducting the operation for finding the substance capable ofsatisfying the condition as described above by using the above-mentionedmethod. Referring to the third aspect of the present invention, it canbe found that SiC (silicon carbide) is particularly appropriate on highmelting metal silicide W-Si, based on which the present invention hasbeen completed.

This invention can suitably be used in a case of forming a stable resistpattern on a W-Si film by using a KrF excimer laser, in which SiC withn=3.16±0.02 and k=0.24±0.05 at a film thickness of 50±50 nm ispreferably used as the anti-reflective layer. SiC constituting theanti-reflective layer can be formed by sputtering or CVD. SiC can beetched by RIE using CF₄, CHF₃, C₂ F₆, C₃ F₈, SF₆ or NF₃ series gas as anetchant and by adding Ar to improve the ionic property.

Further, in the fourth aspect of the present invention, the concept ofthe first aspect is applied in a case of using a metal series materialsuch as a high melting metal compound as the underlying material.

Referring to the fifth aspect of the present invention, upon forming aresist pattern by forming a resist on an anti-reflective layer, when anoperation of finding out the substance capable of satisfying thecondition in accordance with the condition obtained by theabove-mentioned method is conducted, it has been found that SiC (siliconcarbide) and SiO (silicon oxide) are suitable on a metal wiringmaterial, particularly Al series metal material, for example, Al, Al-Si,Al-Si-Cu or Cu series metal material, such as Cu, as well as that anorganic or inorganic material found by the above-mentioned method isappropriate, based on which the present invention has been attained.

This invention is preferably applied in a case of forming a stableresist pattern on an Al series metal material, such as Al, Al-Si orAl-Si-Cu, or a Cu series metal material, such as Cu, by using a KrFexcimer laser. In this case, it is preferred to use SiO with n=1.83±0.2and k=0.75±0.2 at a layer thickness of 30±10 nm as an anti-reflectivelayer, for example, on the Al series metal material. Alternatively, SiCwith n=0.2±0.2 and k=0.8±0.2 is preferably used at a layer thickness of20±10 nm. Alternatively, it is preferred to use an organic or inorganicsubstance having an optimum curve regarding the refractive index and thelayer thickness of the anti-reflective layer obtained in (V) above, andwithin a range of the value on the curve ±0.2 for n and the value on thecurve ±0.15 for k. SiO constituting the anti-reflective layer can beformed by CVD or thermal oxidation. SiC can be formed by sputtering orCVD. The anti-reflective layer can be etched by RIE using CF₄, CHF₃, C₂F₆, C₃ H₈, SF₆ or NF₃ series gas as an etchant and adding Ar and O₂ toimprove the ionic property.

In the sixth aspect of the present invention, the concept of the firstaspect is applied in a case of using an inorganic substance, such assilicon material, as an underlying material.

Referring to the seventh aspect of the present invention, when anoperation was conducted in accordance with the condition obtained in theforegoing method and finding a substance capable of satisfying thecondition, it has been found that SiC (silicon carbide) or SiO isappropriate on a silicon series material, particularly a siliconsubstrate, based on which the present invention has been attained.

The invention can suitably be applied to a case of forming a stableresist pattern on a silicon substrate by using a KrF excimer layer. Inthis case, it is preferred to use SiC with n=0.2±0.2 and k=0.65±0.2 at alayer thickness of 25 nm±10 nm as an anti-reflective layer.Alternatively, it is preferred to use SiO with n=0.1±0.2 and k=0.7±0.2at a layer thickness of 30±10 nm. SiO consisting the anti-reflectivelayer can be formed, for example, by CVD or thermal oxidation. SiC canbe formed, for example, by sputtering or CVD. The anti-reflective layercan be etched by RIE using CF₄, CF₃, C₂ F₆, C₃ H₈, SF₆ or NF₃ series gasas an etchant and adding Ar and O₂ or Ar or O₂ to improve the ionicproperty.

Referring to the ninth and tenth aspects of the present invention, ithas been found that SiO_(x) film, SiO_(x) N_(z) film or SiN_(y) film isappropriate on a metal material such as high melting metal silicide inaccordance with the condition obtained by the method as described above,based on which the present invention has been attained.

This invention is applicable preferably to a case of forming a stableresist pattern on a W-Si film by using a KrF excimer laser. In thiscase, as the anti-reflective layer, it is preferred to use SiO_(x) withn=2.4±0.6 and k=0.7±0.2 at a layer thickness of 30 nm, and further,SiO_(x) can be formed by various kinds of CVD processes. Further,SiO_(x) can be etched by RIE using CHF₃, C₄ F₈, CHF₃ or S₂ F₂ series gasas an etchant and improving the ionic property.

Referring to the 12th and 13th aspects of the present invention, it hasbeen found that a SiO_(x) N_(y) film is suitable on the underlying metalmaterial such as Al series material, based on which the presentinvention has been attained.

Further, referring to the 14th and 15th aspects of the presentinvention, it has been found that a SiO_(x) N_(y) film or Si_(x) N_(y)film is appropriate on the silicon series underlying material, based onwhich the present invention has been attained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart illustrating the constitution of the steps forthe method of determining an optimum condition according to the presentinvention;

FIG. 2 is a graph illustrating a standing wave effect of absorption inrelation to resist thickness;

FIG. 3 is a graph illustrating a trace of fluctuation for the amount ofabsorbed light in a resist film (an equi-contour line for the amount ofabsorbed light) in a case where n_(arl), k_(arl) are varied while fixingthe thickness of the anti-reflective layer ARL, with respect to acertain resist film thickness of 985 nm;

FIG. 4 is a graph illustrating a trace (equi-contour line) for a resistfilm thickness of 1000 nm;

FIG. 5 is a graph illustrating a trace (equi-contour line) for a resistfilm thickness of 1018 nm;

FIG. 6 is a graph illustrating a trace (equi-contour line) for a resistfilm thickness of 1035 nm;

FIG. 7 is a graph illustrating the standing wave effect to be solved;

FIG. 8 is a graph of a trace of fluctuations for the amount of absorbedlight in the resist film relative to variation of n_(arl), k_(arl),(equi-contour lines of absorbed light amount) for the resist filmthickness of 985 nm in a case where the thickness of the anti-reflectivelayer is 30 nm;

FIG. 9 is a graph illustrating a trace (equi-contour lines) for theresist film thickness of 1000 nm;

FIG. 10 is a graph illustrating the trace (equi-contour lines) for theresist film thickness of 1017.5 nm;

FIG. 11 is a graph illustrating the trace (equi-contour lines) for theresist film thickness of 1035 nm;

FIG. 12 is a graph illustrating the standing wave effect at the optimumcondition (Example 1);

FIG. 13 is a graph illustrating the standing wave effect at the optimumcondition (Example 1);

FIG. 14 is a graph illustrating a relationship between the thickness ofthe anti-reflective layer and reflection refractive index n as theoptical condition;

FIG. 15 is a graph illustrating a relationship between the thickness ofthe anti-reflective layer and absorptive refractive index k as theoptical condition;

FIG. 16 is a chart illustrating n, k values for different reflectivelayer material;

FIG. 17 is a graph illustrating the effect of an anti-reflective layerof SiC (50 nm film thickness) on W-Si in comparison with the prior art;

FIG. 18 is a diagrammatic view for the explanation of a problem in theprior art, which shows the interference of light in the resist film;

FIG. 19 is a graph for the explanation of a problem in the prior art,which shows the standing wave effect;

FIG. 20 is a graph for the explanation of a problem in the prior art,which shows the standing wave effect;

FIG. 21 is a graph for the explanation of a problem in the prior art,which shows the standing wave effect;

FIG. 22 is a diagrammatic cross sectional view for the explanation of aproblem in the prior art, which shows the effect of a step;

FIG. 23 is a graph illustrating the effect of the standing wave effect;

FIG. 24 is a graph illustrating the effect of the standing wave effect;

FIG. 25 is a graph showing the effect of the standing wave effect;

FIG. 26 is a graph illustrating a relationship between the fluctuationfor the amount of absorbed light and the dimensional variation of thepattern;

FIG. 27 is a cross sectional view for a portion illustrating thestructure of Example 7;

FIG. 28 is a cross sectional view for a portion illustrating thestructure of Example 14;

FIG. 29 is a graph illustrating the standing wave effect;

FIG. 30 is a graph of a trace of fluctuations for the amount of absorbedlight in the resist film relative to variation of n_(arl), k_(arl),(equi-contour lines of absorbed light amount) for the resist filmthickness of 982 nm in a case where the thickness of the anti-reflectivelayer is 30 nm;

FIG. 31 is a graph illustrating the trace (equi-contour lines) for theresist film thickness of 1000 nm;

FIG. 32 is a graph illustrating the trace (equi-contour lines) for theresist film thickness of 1018 nm;

FIG. 33 is a graph illustrating the trace (equi-contour lines) for theresist film thickness of 1035 nm;

FIG. 34 is a graph illustrating the standing wave effect at the optimumcondition;

FIG. 35 is a graph illustrating the standing wave effect at the optimumcondition;

FIG. 36 is a graph illustrating a relationship between the filmthickness and k as the optical condition of the anti-reflective film;

FIG. 37 is a graph illustrating the dependence of n, k values of the SiCfilm on the film forming condition;

FIG. 38 is a graph illustrating the effect of an anti-reflective layerof SiC (20 nm film thickness) on Al, Al-Si, Al-Si-Cu in comparison witha comparative case;

FIG. 39 is a graph illustrating the effect of an anti-reflective layerof SiO (30 nm film thickness) on Al, Al-Si, Al-Si-Cu in comparison withthe comparative case;

FIG. 40 is a cross sectional view for a portion illustrating thestructure of Example 34;

FIG. 41 is a graph illustrating the standing wave effect;

FIG. 42 is a graph illustrating the effect of an anti-reflective layerof SiC film (25 nm) on a silicon substrate in comparison with acomparative case;

FIG. 43 is a graph illustrating the effect of an anti-reflective layerof SiO film (30 nm) on a silicon substrate in comparison with acomparative case;

FIG. 44 is a cross sectional view illustrating the structure of Example43;

FIG. 45 is a graph illustrating the behavior of SiO film formation byCVD;

FIG. 46 is a graph illustrating the effect of an anti-reflective layerof SiO (24 nm) on W-Si;

FIG. 47 is a cross sectional view illustrating the structure of Example53;

FIG. 48 is a graph illustrating the behavior in forming a Si_(x) O_(y)N_(z) film by CVD;

FIG. 49 is a graph illustrating the effect of an anti-reflective layerof Si_(x) O_(y) N_(z) (25 nm) on W-Si;

FIG. 50 is a cross sectional view illustrating the structure of Example65;

FIG. 51 is a graph illustrating the optical constant property of Si_(x)O_(y) N_(z) or Si_(x) N_(y) ;

FIG. 52 is a graph illustrating the standing wave effect at the optimumcondition in Example 65;

FIG. 53 is a cross sectional view showing the structure of Example 77;

FIG. 54 is a graph illustrating the effect of an anti-reflective layerof a Si_(x) O_(y) N_(z) film or Si_(x) N_(y) film (32 nm) on Si;

FIG. 55 is a graph illustrating the effect of an anti-reflective layerof a Si_(x) O_(y) N_(z) film or Si_(x) N_(y) film (100 nm) on Si;

FIG. 56 is a graph illustrating the optical constant property of Si_(x)O_(y) N_(z) or Si_(x) N_(y) ;

FIG. 57 is a graph illustrating the effect of an anti-reflective layerof the Si_(x) O_(y) N_(z) film or Si_(x) N_(y) film (33 nm) on the Siseries material;

FIG. 58 is a graph for Example 90, which shows the relationship betweencurrent ratio SiH₄ /N₂ O and n, k values of the formed film of SiO_(x)N_(y) ;

FIG. 59 is a graph for Example 90, which shows relationship betweencurrent ratio SiH₄ /N₂ O and the element ratio for each of Si, O, N, H(RBS value) of the formed film of SiO_(x) N_(y) ;

FIG. 60 is a graph illustrating the IR spectrum of film formed inExample 90;

FIG. 61 is a graph illustrating the ordinarily used current ratio ofSiH₄ /N₂ O for forming the SiO_(x) N_(y) film;

FIG. 62 is a graph illustrating the effect of an anti-reflective layerof the film formed in Example 90 on W-Si with SiO₂ ;

FIG. 63 is a graph illustrating the effect of an anti-reflective layerof the film formed in Example 90 on Al-Si;

FIG. 64 is a graph illustrating the effect of an anti-reflective layerof the film formed in Example 90;

FIG. 65 is a graph illustrating the effect of an anti-reflective layerof the film formed in Example 90;

FIG. 66 is a graph illustrating the effect of an anti-reflective layerof the film formed in Example 90;

FIG. 67 is a graph illustrating the operation of Example 90; and

FIG. 68 is a graph illustrating the operation of Example 90.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principles of the present invention will be apparent from thedescription of the following examples. However, the present invention isnot limited by the following examples:

EXAMPLE 1

In this example, the present invention is applied to a determination ofconditions to be satisfied by an anti-reflective layer (layer thickness,optical constant) for forming a stable pattern on a W-Si film by usingan KrF excimer lithography. This example is practiced in accordance withthe following steps (1)-(6):

(1) FIG. 7 shows a standing wave effect when XP 8843 resist (ShipleyMicroelectronics Co.) was coated on a W-Si film without ananti-reflective layer and exposed by an KrF excimer laser beam at awavelength of 248 nm, followed by development. From FIG. 7, the standingwave effect was about ±20%.

(2) In FIG. 7, the maximum value of the standing wave effect is at aresist film thickness, for example, of 985 nm. FIG. 8 shows thefluctuation for the amount of absorbed light in the resist film relativeto the change of optical constants n_(arl) and k_(arl) of theanti-reflective layer (equi-contour lines for the amount of absorbedlight), taking notice on the resist film thickness of 985 nm and settingthe layer thickness of the anti-reflective layer at 30 nm. In FIG. 8, aW-Si layer has an anti-reflective layer of 30 nm thickness covered by aresist film of 985 nm thickness.

(3) FIGS. 9, 10 and 11 show the results of repeating the procedures (2)above to each of the resist film thicknesses of 1000 nm, 1017.5 nm and1035 nm, respectively.

(4) As a result of determining a common region of FIGS. 8-11,

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67

were obtained.

That is, the condition to be satisfied by the optimum anti-reflectivelayer with the thickness of the anti-reflective layer being set as 30 nmis:

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67.

When the standing wave effect was determined by using theabove-mentioned condition, the results shown in FIGS. 12 and 13 wereobtained, with FIG. 12 having n_(arl) =2.15, k_(arl) =0.67 and FIG. 13having n_(arl) =4.9 and k_(arl) =0.1. In FIGS. 12 and 13, the standingwave effect was extremely small and it was about ±1% in each of thecases. The standing wave effect was reduced to about 1/20 as comparedwith the case of not using the anti-reflective layer.

(5) The procedures (2)-(4) described above were conducted in a case ofsetting the thickness of the anti-reflective layer as 30 nm. When theprocedures (2)-(4) were repeated also for other different layerthicknesses of anti-reflective layers (ARL thickness), an optimumcondition for the anti-reflective layer in accordance with the thicknessof the anti-reflective layer can be determined. FIGS. 14 and 15 show theobtained results, with FIG. 14 showing the relationship for n and FIG.15 showing the relationship for k.

(6) It was investigated as to whether the film species capable ofsatisfying the condition to be met by the anti-reflective layerdetermined in (5) above is present or not, by using a spectroscopicellipsometer ("MOSS System" manufactured by SOPRA Co.) and "Handbook ofOptical Constants of Solids" (E. D. Palik, Academy press, 1985). As aresult, an n, k chart shown in FIG. 16 was obtained. Substances havingcorresponding n, k are shown on the chart. From FIG. 16, it has beenfound that SiC (silicon carbide) at 50 nm can completely satisfy theconditions in FIGS. 14 and 15. FIG. 17 shows the standing wave effect inthe case of using SiC at 50 nm thickness as an anti-reflective layer onW-Si and in a case of not using the anti-reflective layer. In a case ofusing SiC at 50 nm as the anti-reflective layer (graph for "with ARL" inthe Figure), the standing wave effect was ±1%, which was reduced toabout 1/20 as compared with the case of not using the anti-reflectivelayer (graph for "without ARL" in the Figure).

EXAMPLE 2

In this example, an anti-reflective layer was formed by forming a SiCfilm with n=3.16±0.2 and k=0.24±0.1 shown in Example 1 by the followingmethod:

That is, in this example, a film was formed by utilizing a thermal CVDprocess at a temperature of 100° C. to 1500° C. and under a pressure of0.01 to 10,000 Pa by using the following gas as the starting materialgas:

    SiCl.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiHCl.sub.3 +C.sub.3 H.sub.8 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiH.sub.4 +C.sub.2 H.sub.4 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiCl.sub.3 +CH.sub.3 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2 or

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2.

Thus, SiC film having a desired anti-reflective effect could beobtained.

EXAMPLE 3

In this example, a SiC film was formed as below to obtain ananti-reflective layer.

That is, in this example, a film was formed by utilizing a plasma CVDprocess and using a photochemical reaction from a gas mixturecomprising: Si₂ H₆ +Si(CH₃)H₃ +C₂ H₂.

EXAMPLE 4

In this example, a SiC film was formed as below to obtain ananti-reflective layer.

A film was formed by utilizing an ECR plasma process using a microwave(2.45 GHz) from a gas mixture comprising: SiH₄ +CH₄ +H₂.

EXAMPLE 5

In this example, a SiC film was formed as below to obtain ananti-reflective layer. That is, a film was formed by utilizing asputtering method using SiC as a target.

EXAMPLE 6

In this example, an anti-reflective layer was formed by patterning a SiCfilm by etching.

In this case, the SiC film was etched by a reactive ion etching processusing a CF₄, CHF₃, C₂ F₆, C₃ F₈, SF₆ or NF₃ series gas as an etchant andadding Ar to improve the ionic property, thereby obtaining ananti-reflective layer of a desired pattern.

EXAMPLE 7

In this example, the present invention was applied by using SiC as ananti-reflective layer for forming a stable pattern on a W-Si film usingKrF excimer lithography.

In the method of forming a resist pattern in this example, as shown inFIG. 27, an anti-reflective layer ARL was formed with silicon carbide ona W-Si underlying material which was a high melting metal silicide and aphotoresist PR was formed on the anti-reflective layer ARL, therebyforming a resist pattern.

In this example, the present invention is applied by using SiC as theanti-reflective layer ARL, particularly in a case of forming a materiallayer with W-Si as a gate, on a substrate, such as an Si semiconductorsubstrate and patterning the same by a photolithographic step using aphotoresist PR and an etching step, thereby obtaining a gate structure.

At first, description will be made to the procedures for selecting SiCas the anti-reflective layer to be used on W-Si and a method ofdetermining a condition to be satisfied by SiC. The following procedures(1)-(6) were conducted:

(1) XP 8843 resist (Shipley Microelectronics Co.) was coated on a W-Sifilm without an anti-reflective layer, which resist was exposed by anKrF excimer laser beam at a wave length of 248 nm, followed bydevelopment. FIG. 7 shows a standing wave effect in this case. From FIG.7, the standing wave effect was about ±20%.

(2) In FIG. 7, the maximum value of the standing wave effect is at aresist film thickness, for example, of 985 nm. FIG. 8 shows fluctuationfor the amount of absorbed light in the resist film relative to thechange of optical constants n_(arl) and k_(arl) of the anti-reflectivelayer, which is between the resist film and W-Si film. The resist filmhas a thickness of 985 nm and the layer thickness of the anti-reflectivelayer is set to 30 nm.

(3) FIGS. 9, 10 and 11 show the results of repeating the procedures (2)above to each of the resist film thicknesses of 1000 nm, 1017.5 nm and1035 nm, respectively.

(4) As a result of determining a common region in FIGS. 8-11:

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67

were obtained.

That is, the condition to be satisfied by the optimum anti-reflectivelayer with the thickness of the anti-reflective layer being set as 30 nmis:

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67.

When the standing wave effect was determined by using theabove-mentioned condition, the results shown in FIGS. 12 and 13 wereobtained. In FIGS. 12 and 13, the standing wave effect was extremelysmall and it was about ±1% in each of the cases. The standing waveeffect was reduced to about 1/20 as compared with the case of not usingthe anti-reflective layer.

(5) The procedures (2)-(4) described above were conducted in a case ofsetting the thickness of the anti-reflective layer as 30 nm. When theprocedures (2)-(4) were repeated also for other different layerthicknesses of anti-reflective layer (ARL thickness), an optimumcondition for the anti-reflective layer in accordance with the thicknessof the anti-reflective layer could be determined. FIGS. 14 and 15 showthe obtained results.

(6) It was investigated as to whether the film species capable ofsatisfying the condition to be met by the anti-reflective layerdetermined in (5) above is present or not by using a spectroscopicellipsometer ("MOSS System" manufactured by SOPRA Co.) and "Handbook ofOptical Constants of Solids" (E. D. Palik, Academy Press, 1985). As aresult, an n, k chart shown in FIG. 16 was obtained. Substances havingcorresponding n, k are shown on the chart. From FIG. 16, it has beenfound that SiC (silicon carbide) at 50 nm can completely satisfy theconditions in FIGS. 14 and 15. FIG. 17 shows the standing wave effect ina case of using SiC at 50 nm thickness as the anti-reflective layer onW-Si and in a case of not using the anti-reflective layer. In a case ofusing SiC at 50 nm as the anti-reflective layer (graph for "with ARL" inthe Figure), the standing wave effect was ±1%, which was reduced toabout 1/20 as compared with the case of not using the anti-reflectivelayer (graph for "without ARL" in the Figure).

EXAMPLE 8

In this example, an anti-reflective layer was formed by forming an SiCfilm with n=3.16±0.2 and k=0.24±0.1 shown in Example 1 by the followingmethods.

That is, in this example, a film was formed by utilizing a thermal CVDprocess at a temperature of 100° C. to 1500° C. and under a pressure of0.01 to 10,000 Pa by using the following gas as the starting material:

    SiCl.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiHCl.sub.3 +C.sub.3 H.sub.8 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiH.sub.4 +C.sub.2 H.sub.4 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiCl.sub.3 +CH.sub.3 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2 or

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2.

Thus, SiC films having a desired anti-reflective effect could beobtained.

EXAMPLE 9

In this example, a SiC film was formed as below to obtain ananti-reflective layer.

That is, in this example, e film was formed by utilizing a plasma CVDprocess and using a photochemical reaction for a gas mixture comprising:Si₂ H₆ +Si(CH₃)H₃ +C₂ H₂.

EXAMPLE 10

In this example, a SiC film was formed as below to obtain ananti-reflective layer.

A film was formed by utilizing an ECR plasma process using a microwave(2.45 GHz) from a gas mixture comprising: SiH₄ +CH₄ +H₂.

EXAMPLE 11

In this example, a film was formed by utilizing an ECR plasma CVDprocess from SiH₄ +C₂ H₄ gas by a plasma process using a microwave at2.45 GHz.

EXAMPLE 12

A SiC film was formed as below to obtain an anti-reflective layer. Afilm was formed by a sputtering method using SiC as a target.

EXAMPLE 13

In this example, an anti-reflective layer was formed by patterning a SiCfilm by etching.

In this case, the SiC film was etched by a reactive ion etching processusing CF₄, CHF₃, C₂ F₆, C₃ F₆, SF₆ or NF₃ series gas (or a mixed gassystem) as an etchant and adding Ar to improve the ionic property,thereby obtaining an anti-reflective layer of a desired pattern.

EXAMPLE 14

In this example, the present invention was applied by using SiC as theanti-reflective layer for forming a stable pattern on an Al, Al-Si orAl-Si-Cu film as the Al series material using KrF excimer lithography,

As shown in FIG. 28, in the method of forming the resist pattern in thisexample, an anti-reflective layer ARL was formed with silicon carbide onAl, Al-Si or Al-Si-Cu as an Al series metal wiring material (1) andforming a photoresist PR on the anti-reflective layer ARL therebyforming a resist pattern.

In this example, the present invention was applied, particularly, in thecase of obtaining a wiring structure by forming a material layer as awiring with Al, Al-si or Al-Si-Cu on a substrate S, such as a Sisemiconductor substrate, and patterning the same by a photolithographicstep using the photoresist PR and an etching step, in which SiC was usedas the anti-reflective layer ARL. As Al-Si, there can be preferablyused, in addition to a generally used Al-Si alloy containing 1 wt % Sigenerally used, an alloy with lower or higher Si content. This exampleis preferably applicable to Al-Si-Cu in which Si is about 1 wt % and Cuis about 0.1 to 2 wt %, with no particular restriction only thereto.Typically, Al-Si-Cu alloy of 1 wt % Si, 0.5 wt % Cu is used.

At first, a description will be made of the procedures for selecting SiCas an anti-reflective layer used on Al, Al-Si or Al-Si-Cu as the Alseries metal, as well as a method of determining the condition to besatisfied by SiC. The following procedures (1)-(6) were conducted.

(1) XP 8843 resist (manufactured by Shipley Microelectronics Co.) wascoated on an Al, Al-Si or Al-Si-Cu film without an anti-reflective layerand exposed by a KrF excimer laser beam at a wave length of 248 nm,followed by development. FIG. 29 shows the standing wave effect in thiscase. As shown in FIG. 29, the standing wave effect was about ±29.6%.

(2) In FIG. 29, the maximum value of the standing wave effect situates,for example, at 982 nm of the resist film thickness. FIG. 30 shows thefluctuation for the amount of absorbed light (equi-contour lines for theamount of absorbed light) in the resist film relative to the change ofoptical constants n_(arl), k_(arl) of the anti-reflective layer that isbetween the resist layer and the Al, Al-Si or Al-Si-Cu film. The resistfilm has a thickness of 982 nm, and the thickness of the anti-reflectivelayer is set at 30 nm.

(3) FIGS. 31, 32 and 33 show results of repeating the procedure (2)described above for the resist film thicknesses of 1000 nm, 1018 nm and1035 nm, respectively.

(4) As a result of determining a common region in FIG. 30 to FIG. 33,

    n.sub.arl =4.8, k.sub.arl =0.45, or

    n.sub.arl =2.0, k.sub.arl =0.8

was obtained.

That is, the condition to be satisfied by the optimum anti-reflectivelayer upon setting the thickness of the anti-reflective layer as 30 nmwas:

    n.sub.arl =4.8, k.sub.arl =0.45, or

    n.sub.arl =2.0, k.sub.arl =0.8.

When the standing wave effect was determined by using this condition,results shown by the "optimum condition" in FIG. 34 and FIG. 35 wereobtained. As apparent from the comparison with "without anti-reflectivelayer" in FIGS. 34 and 35, the standing wave effect was extremely small,which was about less than ±1% in each of the cases. As compared with thecase without anti-reflective layer, the standing wave effect was reducedto about 1/30.

(5) The procedures (2)-(4) above are for the case of setting thethickness of the anti-reflective layer to 30 nm. When the procedures(2)-(4) were repeated also to the anti-reflective layers of differentthicknesses (ARL thickness), the optimum condition for theanti-reflective layer depending on the thickness of the anti-reflectivelayer was determined. FIGS. 14 and 36 show the, thus, obtained results.

(6) It was investigated as to whether the film species capable ofsatisfying the condition to be met by the anti-reflective layer obtainedin (5) described above are present or not, by using a spectroscopicellipsometer ("MOSS System", manufactured by SOPRA Co.) and "Handbook ofOptical Contacts of Solids" (E. D. Palik, Academy Press, 1985). As aresult, an n, k chart was obtained as shown in FIG. 16. Substanceshaving corresponding n, k are shown on the chart. From FIG. 16, it hasbeen found that SiC (silicon carbide) at 20 nm can completely satisfythe conditions in FIGS. 14 and 36. FIG. 38 shows the standing waveeffect in a case of using or not using SiC at 20 nm as ananti-reflective layer on Al, Al-Si or Al-Si-Cu. The standing wave effectin a case of using SiC at 20 nm as the anti-reflective layer (graph for"with ARL" in FIG. 38) was ±2.2 (1.4%) and the standing wave effect wasreduced to about 1/15 compared with the case of not using theanti-reflective layer (graph for "without ARL" in the Figure). FIG. 37shows the dependence of n, k values of the SiC film on the film formingcondition.

EXAMPLE 15

In this example, an anti-reflective layer as shown in FIG. 28 was formedby forming a SiC film with n=2.3±0.2 and k=0.8±0.2 shown in Example 1 bythe following method.

That is, in this example, a film was formed by utilizing a thermal CVDprocess at a temperature of 100° C. to 1500° C. and usually under apressure, preferably 0.01 to 10,000 Pa, more preferably, 100 to 10,000Pa by using the following gas as the starting material gas:

    SiCl.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiHCl.sub.3 +C.sub.3 H.sub.6 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiH.sub.4 +C.sub.2 H.sub.4 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiCl.sub.3 +CH.sub.3 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2 or

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2.

Thus, a SiC film having an aimed anti-reflective effect could beobtained.

EXAMPLE 16

In this example, a SiC film was formed as below to obtain ananti-reflective layer. That is, in this example, a film was formed byutilizing a plasma CVD process and using a photochemical reaction in agas mixture comprising: Si₂ H₆ +Si(CH₃)H₃ +C₂ H₂.

EXAMPLE 17

In this example, a SiC film was formed as below to obtain ananti-reflective layer.

A film was formed by an ECR plasma process by utilizing an ECR plasmaCVD process using a microwave (at 2.45 GHz) from a gas mixturecomprising SiH₄ +CH₄ +H₂, SiH₄ +C₂ H₄ +H₂ or SiH₄ +CH₄ +H₂.

EXAMPLE 18

In this example, an SiC film was formed as below to obtain ananti-reflective layer. That is, a film was formed by utilizing asputtering method using SiC as a target.

EXAMPLE 19

In this example, an anti-reflective layer was formed by patterning a SiCfilm by etching.

In this case, the SiC film was etched by a reactive ion etching processusing a CF₄, CHF₃, C₂ F₆, C₃ F₈, SF₆ or NF₃ series gas as an etchant andadding Ar to improve the ionic property, thereby obtaining ananti-reflective layer of a desired pattern.

EXAMPLE 20

In this example, the present invention was applied by using SiO as ananti-reflective layer for forming a stable pattern on an Al, Al-Si orAl-Si-Cu film using KrF excimer lithography.

In the method of forming a resist pattern in this example, as shown inFIG. 28, an anti-reflective layer ARL was formed with silicon oxide SiOon an Al, Al-Si or Al-Si-Cu as the Al series metal wiring material and aphotoresist PR was formed on the anti-reflective layer ARL, therebyforming the resist pattern.

In this example, the present invention was applied by using SiO as theanti-reflective layer ARL, particularly in a case of forming a materiallayer as a wiring with Al, Al-Si or Al-Si-Cu on a substrate S, such as aSi semiconductor substrate, and patterning the same by aphotolithographic step using a photoresist PR and an etching step,thereby obtaining a gate structure.

At first, description will be made to procedures for selecting SiO asthe anti-reflective layer to be used on Al, Al-Si or Al-Si-Cu as the Alseries material and a method of determining a condition to be satisfiedby SiO. The following procedures (1)-(6) were conducted in the samemanner as in Example 14.

(1) XP 8843 resist (Shipley Microelectronics Go.) was coated on an Al,Al-Si or Al-Si-Cu film without an anti-reflective layer and exposed byan KrF excimer laser beam at a wavelength of 248 nm, followed bydevelopment. FIG. 29 shows a standing wave effect in this case. FromFIG. 29, the standing wave effect was about ±29.6%.

(2) In FIG. 29, the maximum value of the standing wave effect is at aresist film thickness, for example, of 982 nm. FIG. 30 shows fluctuationfor the amount of absorbed light in the resist film relative to thechange of optical constants n_(arl) and k_(arl) of the anti-reflectivelayer, which is between the resist layer and the layer of Al, Al-Si orAl-Si-Cu. The resist film thickness is 982 nm and the layer thickness ofthe anti-reflective layer is set at 30 nm.

(3) FIGS. 31, 32 and 33 show the results of repeating the procedures (2)above to each of the resist film thicknesses of 1000 nm, 1018 nm and1035 nm, respectively.

(4) As a result of determining a common region in FIGS. 30 to 33,

    n.sub.arl =4.8, k.sub.arl =0.45, or

    n.sub.arl =2.0, k.sub.arl =0.8

were obtained.

That is, the condition to be satisfied by the optimal anti-reflectivelayer with the thickness of the anti-reflective layer being set at 30 nmis:

    n.sub.arl =4.8, k.sub.arl =0.45, or

    n.sub.arl =2.0, k.sub.arl =0.8.

When the standing wave effect was determined by using theabove-mentioned condition, the results shown in FIG. 34 and FIG. 35 asdescribed in Example 14 were obtained. In FIG. 34 and FIG. 35, thestanding wave effect was extremely small and it was about less than ±1%in each of the cases. The standing wave effect was reduced to about 1/30as compared with the case of not using the anti-reflective layer.

(5) The procedures (2)-(4) described above were conducted in a case ofsetting the thickness of the anti-reflective layer as 30 nm. When theprocedures (2)-(4) were repeated also for anti-reflective layer (ARLthickness) of other different layer thicknesses, an optimal conditionfor the anti-reflective layer in accordance with the thickness of theanti-reflective layer could be determined. FIG. 14 and FIG. 36 show theobtained results.

(6) It was investigated as to whether the film species capable ofsatisfying the condition to be met by the anti-reflective layerdetermined in (5) above are present or not by using a spectroscopicellipsometer ("MOSS System" manufactured by SOPRA Co.) and "Handbook ofOptical Constants of Solids" (E. D. Palik, Academy Press, 1985). As aresult, an n, k chart shown in FIG. 16 was obtained. Substances havingcorresponding n, k are shown on the chart. From FIG. 16, it has beenfound that SiO (silicon oxide) at 30 nm can completely satisfy theconditions in FIG. 14 and FIG. 36. FIG. 39 shows the standing waveeffect in a case of using SiO at 50 nm thickness as the anti-reflectivelayer on Al, Al-Si or Al-Si-Cu and in a case of not using theanti-reflective layer. In a case of using SiO at 30 nm as theanti-reflective layer (graph for "with SiO" in the Figure), the standingwave effect was ±2.2% (1.4%), which was reduced to about 1/20 ascompared with the case of not using the anti-reflective layer (graph for"without SiO" in the Figure).

EXAMPLE 21

In this example, an anti-reflective layer was formed by forming a SiOfilm with n=1.83±0.2 and k=0.75±0.2 shown in Example 20 by the followingmethod.

That is, in this example, a film was formed at a temperature from normaltemperature to 500° and under a pressure of 0.01 to 10 Pa by using a gasmixture of SiH₄ +O₂ +N₂. Thus, a SiO film having an aimedanti-reflective effect could be obtained.

EXAMPLE 22

In this example, an anti-reflective layer was formed by patterning a SiOfilm by etching.

In this case, the SiO film was etched by a reactive ion etching processusing CF₄, CHF₃, C₂ F₆, C₃ F₈, SF₆ or NF₃ series gas (or a mixed gassystem) as an etchant and adding Ar to improve the ionic property,thereby obtaining an anti-reflective layer of a desired pattern.

EXAMPLE 23

In this example, an organic or inorganic substance suitable for forminga stable pattern on an Al, Al-Si or Al-Si-Cu film was obtained and usingit as an anti-reflective layer by using KrF excimer lithography.

As shown in FIG. 28, in the method of forming the resist pattern in thisexample, an anti-reflective layer ARL was formed on Al, Al-Si orAl-Si-Cu as an Al series metal wiring material (1) and forming aphotoresist PR on the anti-reflective layer ARL, thereby forming aresist pattern, in which an appropriate material was selected to formthe anti-reflective layer.

In this example, the anti-reflective layer was designed, particularly ina case of obtaining a wiring structure by forming a material layer aswiring with Al, Al-Si, or Al-Si-Cu on a substrate S, such as a Sisemiconductor substrate, and patterning the same by photolithographicstep using the photoresist PR and an etching step.

(1) XP 8843 resist (manufactured by Shipley Microelectronics Co.) wascoated on an Al, Al-Si or Al-Si-Cu film without an anti-reflective layerand exposed by a KrF excimer laser beam at a wavelength of 248 nm,followed by development. FIG. 29 shows the standing wave effect in thiscase. As shown in FOG. 29, the standing wave effect was about ±29.6%.

(2) In FIG. 29, the maximum value of the standing wave effect situates,for example, at 982 nm of the resist film thickness. FIG. 30 showsfluctuation for the amount of absorbed light in the resist film relativeto the change of optical constants n_(arl), k_(arl) of theanti-reflective layer. The resist film has a thickness of 982 nm, andthe thickness of the anti-reflective layer is set to 30 nm.

(3) FIGS. 31, 32 and 33 show the results of repeating the procedure (2)described above to each of resist film thicknesses of 1000 nm, 1018 nmand 1035 nm, respectively.

(4) As a result of determining a common region in FIG. 30 to FIG. 33,

    n.sub.arl =4.8, k.sub.arl =0.45, or

    n.sub.arl =2.0, k.sub.arl =0.8

were obtained.

That is, the condition to be satisfied by the optimum anti-reflectivelayer upon setting the thickness of the anti-reflective layer as 30 nmwas:

    n.sub.arl =4.8, k.sub.arl =0.45, or

    n.sub.arl =2.0, k.sub.arl =0.8.

When the standing wave effect was determined by using this condition,results shown in FIG. 34 and FIG. 35 were obtained. The standing waveeffect shown by "optimum condition" in FIGS. 34 and 35 was extremelysmall, which was about less than ±1% in each of the cases. As comparedwith the case without anti-reflective layer, the standing wave effectwas reduced to about 1/30.

(5) The procedures (2)-(4) above are for the case of setting thethickness of the anti-reflective layer to 30 nm. When the procedures(2)-(4) were repeated also to the anti-reflective layers of differentthicknesses (ARL thickness), the optimum condition for theanti-reflective layer depending on the thickness of the anti-reflectivelayer was determined. FIGS. 14 and 36 show the, thus, obtained results.

The standing wave effect was reduced to less than ±3% by using anorganic or inorganic substance capable of satisfying the opticalproperty on the curve in FIGS. 14 and 36, or within a range of a valueon the curve ±0.2 for n and a value on the curve ±0.15 for k.Accordingly, such an organic or inorganic substance was determined toform an anti-reflective layer. As compared with the case of not usingthe anti-reflective layer, the standing wave effect was reduced to about1/10.

EXAMPLES 24-33

In these examples, Cu wiring was formed by using Cu as the Cu seriesmetal material instead of the Al series metal material, such as Al,Al-Si or Al-Si-Cu, as the underlying material in Examples 14-23, and ananti-reflective layer was formed thereon in the same manner as in eachof the examples (an anti-reflective layer comprising an organic orinorganic substance determined by the same method as in Example 23 in acase where SiC, SiO or Cu was used as the underlying material), therebyperforming the resist patterning.

As a result, the standing wave effect was reduced and satisfactorypatterning was conducted in the same manner as in each of the previousexamples.

EXAMPLE 34

In this example, the present invention was applied by using SiC as ananti-reflective layer for forming a stable pattern on a Si substrateusing KrF excimer lithography.

In the method of forming a resist pattern in this example, as shown inFIG. 40, an anti-reflective layer ARL was formed with silicon carbide ona silicon substrate as the Si series underlying material and aphotoresist PR was formed on the anti-reflective layer ARL, therebyforming the resist pattern.

At first, description will be made to the procedures for selecting SiCas the anti-reflective layer and the method of determining the conditionto be satisfied by SiC. The following procedures were conducted.

(1) XP 8843 resist (manufactured by Shipley Microelectronics Co.) wascoated on a Si substrate without an anti-reflective layer, which wasexposed by a KrF excimer laser beam at a wavelength of 248 nm, followedby development. FIG. 41 shows the standing wave effect in this case. Asshown in FIG. 41, the standing wave effect was about ±20%.

(2) In FIG. 41, the maximum value of the standing wave effect situates,for example, at 985 nm of the resist film thickness. Fluctuation for theamount of absorbed light in the resist film was determined relative tothe change of optical constants n_(arl), k_(arl) of the anti-reflectivelayer, while taking notice on the resist film thickness of 985 nm, andsetting the thickness of the anti-reflective layer to 30 nm.

(3) The procedure (2) was repeated for each of a plurality of otherresist film thicknesses.

(4) The results are shown in the Figures and a common region in them wasdetermined. Such a procedure was determined for each of the filmthicknesses of the anti-reflective layers, by which an optimum value (nvalue, k value) for the optical property of a certain film thickness wasdetermined.

The optimum condition for the anti-reflective layer was determined.Based on the result, SiC having n=2.3 and k=0.65 was used at a layerthickness of 25 nm as the anti-reflective layer, to greatly reduce thestanding wave effect.

FIG. 42 shows a comparison between a case of using SiC at 25 nm as theanti-reflective layer (graph for "with SIC") and a case of not using theanti-reflective layer (graph for "without SIC"). In the case of usingSiC at 25 nm, the standing wave effect was reduced to less than ±1%. Thestanding wave effect in the case of not using SiC was ±23%. Accordingly,the standing wave effect was reduced to less than 1/23 by using SiC asthe anti-reflective layer on Si.

EXAMPLE 35

Also in this example, silicon oxide (SiO) having an optimal condition asthe anti-reflective layer was determined by using the same method as inthe previous example. That is, in this example, SiO having n=2.1, k=0.7was used at a film thickness of 30 nm as the anti-reflective layer togreatly reduce the standing wave effect.

FIG. 43 shows a comparison between a case of using SiO at 30 nm as theanti-reflective layer (graph for "with SiO") and a case of not using theanti-reflective layer (graph for "without SiO"). As in the case of usingSiC at 25 nm in Example 34, the standing wave effect for SiO was about±1%, The standing wave effect in the case of not using SiO was ±23%.Accordingly, the standing wave effect was reduced to less than about1/23 by using SiO as the anti-reflective layer on Si.

EXAMPLE 36

In this example, an anti-reflective layer as shown in FIG. 40 was formedby forming a SiC film with n=2.3±0.2 and k=0.8±0.2 shown in Example 34by the following method.

That is, in this example, a film was formed by utilizing a thermal CVDprocess at a temperature of 100° C. to 1500° C. and usually under apressure, preferably from 0.01 to 10,000 PA, more preferably 100 to10,000 Pa by using the following gas as the staring material gas:

    SiCl.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiHCl.sub.3 +C.sub.3 H.sub.8 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiH.sub.4 +C.sub.2 H.sub.4 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2,

    SiCl.sub.3 +CH.sub.3 +H.sub.2,

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2 or

    SiH.sub.4 +C.sub.3 H.sub.8 +H.sub.2.

Thus, a SiC film having a desired anti-reflective effect could beobtained.

EXAMPLE 37

In this example, an SiC film was formed as below to obtain ananti-reflective layer. That is, in this example, a film was formed byutilizing a plasma CVD process and using a photochemical reaction in agas mixture comprising: Si₂ H₆ +Si(CH₃)H₃ +C₂ H₂.

EXAMPLE 38

In this example, a SiC film was formed as below to obtain ananti-reflective layer.

A film was formed by an ECR plasma process by utilizing an ECR plasmaCVD process using microwave (at 2.45 GHz) from a gas mixture comprising:SiH₄ +CH₄ +H₂, SiH₄ +C₂ H₄ +H₂ or SiH₄ +CH₄ +H₂.

EXAMPLE 39

In this example, a SiC film was formed as below to obtain ananti-reflective layer. That is, a film was formed by utilizing asputtering method using SiC as a target.

EXAMPLE 40

In this example, an anti-reflective layer was formed by patterning a SiCfilm by etching.

In this case, the SiC film was etched by a reactive ion etching processusing CF₄, CHF₃, C₂ F₆, C₃ F₈, SF₆ or NF₃ series gas as an etchant andadding Ar to improve the ionic property, thereby obtaining ananti-reflective layer of a desired pattern.

EXAMPLE 41

In this example, a SiO film having n=2.1±0.2 and k=0.7±0.2 shown inExample 35 was formed by the following method to form an anti-reflectivelayer shown in FIG. 40 and described for the function in FIG. 43.

That is, a film was formed by using a gas mixture of SiH₄ +O₂ +N₂ at atemperature from normal temperature to 500° C. under a pressure of 0.01Pa-10 Pa. Thus, a SiO layer having a desired anti-reflective effect wasobtained.

EXAMPLE 42

The SiC layer and the SiO layer in each of the examples described abovewere formed on the underlying single crystal silicon, underlyingpolycrystalline silicon and underlying amorphous silicon, respectively,to form anti-reflective layers. As a result, a desired anti-reflectiveeffect could be obtained to attain a satisfactory pattern formation.

EXAMPLE 43

In this example, the present invention was applied by using SiO_(x) asan anti-reflective layer for forming a stable pattern on a W-Si filmusing KrF excimer lithography.

In the method of forming a resist pattern in this example, as shown inFIG. 44, an anti-reflective layer ARL was formed with SiO_(x) on anunderlying W-Si material as high melting metal silicide and aphotoresist PR was formed on the anti-reflective layer ARL, therebyforming the resist pattern.

In this example, the present invention is applied by using SiO_(x) asthe anti-reflective layer ARL, particularly in a case of forming amaterial layer as a gate with W-Si on a substrate 1, such as a Sisemiconductor substrate, and patterning the same by a photolithographicstep using a photoresist PR and an etching step, thereby obtaining agate structure.

At first, description will be made to the procedures for selectingSiO_(x) as the anti-reflective layer to be used on W-Si and the methodof determining the condition to be satisfied by SiO_(x). The followingprocedures (1)-(6) were conducted:

(1) XP 8843 resist (manufactured by Shipley Microelectronics Co.) wascoated on W-Si without an anti-reflective layer and exposed by a KrFexcimer laser beam at a wavelength of 248 nm, followed by development.FIG. 7 shows the standing wave effect in this case. As shown in FIG. 7,the standing wave effect was about ±20%.

(2) In FIG. 7, the maximum value of the standing wave effect situates,for example, at 985 nm of the resist film thickness. FIG. 8 shows theequi-contour lines for the amount of absorbed light in the resist filmrelative to the change of optical constants n_(arl), k_(arl) of theanti-reflective layer, with the resist film thickness of 985 nm, and thethickness of the anti-reflective layer set to 30 nm.

(3) FIGS. 9, 10 and 11 show the results of repeating the procedures (2)above to each of the resist film thicknesses of 1000 nm, 1017.5 nm and1035 nm, respectively.

(4) As a result of determining a common region in FIG. 8 to FIG. 11,

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67

were obtained.

That is, the condition to be satisfied by the optimal anti-reflectivelayer with the thickness of the anti-reflective layer being set as 30 nmis:

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67.

When the standing wave effect was determined by using theabove-mentioned condition, the results shown in FIG. 12 and FIG. 13 wereobtained. In each of the cases, the standing wave effect was extremelysmall and it was about less than 1%. The standing wave effect wasreduced to about 1/20 as compared with the case of not using theanti-reflective layer.

(5) The procedures (2)-(4) described above were conducted in a case ofsetting the thickness of the anti-reflective layer as 30 nm. When theprocedures (2)-(4) were repeated also for anti-reflective layer (ARLthickness) of other different layer thicknesses, an optimal conditionfor the anti-reflective layer in accordance with the thickness of theanti-reflective layer could be determined. FIG. 14 and FIG. 15 show theobtained results.

(6) It was investigated as to whether the film species capable ofsatisfying the condition to be met by the anti-reflective layerdetermined in (5) above are present or not by using a spectroscopicellipsometer (SOPRA Go.). As a result, it has been found that theoptical constant shows changes in FIG. 45 corresponding to the filmforming conditions upon forming the SiO, film by using the CVD process.In FIG. 45, regions shown by open circles satisfy the conditions inFIGS. 14 and 15. That is, FIG. 46 shows the standing wave effect in acase of using the SiO_(x) film at 25 nm thickness as an anti-reflectivelayer and in a case of not using the anti-reflective layer. In the caseof using a SiO_(x) film at 25 nm, the standing wave effect was about±1.8% and the standing wave effect was reduced to less than about 1/12as compared with the case of not using the anti-reflective layer.

EXAMPLE 44

In this example, a SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shown inExample 43 was formed by the following method to form an anti-reflectivelayer as shown in FIG. 46.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process and using a microwave (2.45 GHz) from a gasmixture of SiH₄ +O₂.

EXAMPLE 45

In this example, a SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shown inExample 43 was formed by the following method to form an anti-reflectivelayer having an anti-reflective function as shown in FIG. 46.

That is, in this example, a film was formed by utilizing a parallelplate type plasma CVD process and using a microwave (2.45 GHz) from agas mixture of SiH₄ +O₂ and using Ar as a buffer gas.

EXAMPLE 46

In this example, a SiO_(x) film having n=2.4±0.6 and k-0.7±0.2 shown inExample 43 was formed by the following method to form an anti-reflectivelayer having an anti-reflective function as shown in FIG. 46.

That is, in this example, a film was formed by utilizing an ECR typeplasma CVD process and using a microwave (2.45 GHz) from a gas mixtureof SiH₄ +O₂.

EXAMPLE 47

In this example, a SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shown inExample 43 was formed by the following method to form an anti-reflectivelayer having an anti-reflective function as shown in FIG. 46.

That is, in this example, a film was formed by utilizing an ECR typeplasma CVD process and using a microwave (2.45 GHz) from a gas mixtureof SiH₄ +O₂ and using Ar as a buffer gas.

EXAMPLE 48

In this example, a SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shown inExample 43 was formed by the following method to form an anti-reflectivelayer having an anti-reflective function as shown in FIG. 46.

That is, in this example, a film was formed by utilizing a bias ECRplasma CVD process and using a microwave (2.45 GHz) from a gas mixtureof SiH₄ +O₂.

EXAMPLE 49

In this example, a SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shown inExample 43 was formed by the following method to form an anti-reflectivelayer having an anti-reflective function as shown in FIG. 46.

That is, in this example, a film was formed by utilizing a bias ECR typeplasma CVD process and using a microwave (2.45 GHz) from a gas mixtureof SiH₄ +O₂ and using Ar as a buffer gas.

EXAMPLE 50

In this example, the SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shownin Example 3 was etched for the underlying material using a resistpattern as a mask by the following method.

That is, the SiO_(x) film was etched by a reactive etching process usinga gas system of CHF₃ (50-100 SCCM)+O₂ (3-20 SCCM) under a pressure ofabout 2 Pa and with a power of about 100 to 1000 W, to obtain a desiredpattern by etching.

EXAMPLE 51

In this example, the SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shownin Example 43 was etched for the underlying material using a resistpattern as a mask by the following method.

That is, the SiO_(x) film was etched by a reactive etching process usinga gas system of C₄ F₈ (30-70 SCCM)+CHF₃ (10-30 SCCM) under a pressure ofabout 2 Pa and with a power of about 100 to 1000 W, to obtain a desiredpattern by etching.

EXAMPLE 52

In this example, the SiO_(x) film having n=2.4±0.6 and k=0.7±0.2 shownin Example 43 was etched for the underlying material using a resistpattern as a mask by the following method.

That is, the SiO_(x) film was etched by a reactive etching process usinga gas system of S₂ F₂ (5-30 SCCM) under a pressure of about 2 Pa andwith a power of about 100 to 1000 W, to obtain a desired pattern byetching.

EXAMPLE 53

In this example, the present invention was applied by using a Si_(x)O_(y) N_(z) or Si_(x) N_(y) film as an anti-reflective layer for forminga stable pattern on a W-Si film by using KrF excimer lithography.

In the method of forming a resist pattern in this example, as shown inFIG. 47, an anti-reflective layer ARL was formed with Si_(x) O_(y) N_(z)or Si_(x) N_(y) on the underlying W-Si as a high melting metal silicideG and a photoresist PR was formed on the anti-reflective layer ARL,thereby forming the resist pattern.

In this example, the present invention is applied by using Si_(x) O_(y)N_(z) or Si_(x) N_(y) as the anti-reflective layer ARL particularly in acase of forming a material layer with W-Si as a gate on a substrate S,such as a Si semiconductor substrate, and patterning the same by aphotolithographic step using a photoresist PR and an etching step,thereby obtaining a gate structure.

At first, description will be made to the procedures for selectingSi_(x) O_(y) N_(z) or Si_(x) N_(y) as the anti-reflective layer to beused on W-Si and the method of determining the condition to be satisfiedby Si_(x) O_(y) N_(z) or Si_(x) N_(y). The following procedures (1)-(6)were conducted.

(1) XP 8843 resist (manufactured by Shipley Microelectronics Co.) wascoated on W-Si without an anti-reflective layer and exposed by a KrFexcimer laser beam at a wavelength of 248 nm, followed by development.FIG. 7 shows the standing wave effect in this case. As shown in FIG. 7,the standing wave effect was about ±20%.

(2) In FIG. 7, the maximum value of the standing wave effect situated,for example, at 985 nm of the resist film thickness. FIG. 8 showsequi-contour lines for the amount of absorbed light in the resist filmrelative to the change of optical constants n_(arl), k_(arl) of theanti-reflective layer, wherein the resist film has a thickness of 985nm, and the thickness of the anti-reflective layer is set to 30 nm.

(3) FIGS. 9, 10 and 11 show the results of repeating the procedures (2)above to each of the resist film thicknesses of 1000 nm, 1017.5 nm and1035 nm, respectively.

(4) As a result of determining a common region in FIG. 8 to FIG. 11,

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67

were obtained.

That is, the condition to be satisfied by the optimal anti-reflectivelayer with the thickness of the anti-reflective layer being set at 30 nmis:

    n.sub.arl =4.9, k.sub.arl =0.1, or

    n.sub.arl =2.15, k.sub.arl =0.67.

When the standing wave effect was determined by using theabove-mentioned condition, the results shown in FIG. 12 and FIG. 13 wereobtained. In FIG. 12 and FIG. 13, the standing wave effect was extremelysmall and it was about less than ±1% in each of the cases. The standingwave effect was reduced to about 1/20 as compared with the case of notusing the anti-reflective layer.

(5) The procedures (2)-(4) described above were conducted in a case ofsetting the thickness of the anti-reflective layer as 30 nm. When theprocedures (2)-(4) were repeated also for anti-reflective layer (ARLthickness) of other different layer thicknesses, an optimal conditionfor the anti-reflective layer in accordance with the thickness of theanti-reflective layer could be determined. FIG. 14 and FIG. 15 show theobtained results.

(6) It was investigated as to whether the film species capable ofsatisfying the condition to be met by the anti-reflective layerdetermined in (5) above are present or not by using a spectroscopicellipsometer (SOPRA Go.).

As a result, it has been found that the optical constant shows changesin FIG. 48 corresponding to the film forming conditions upon forming theSi_(x) O_(y) N_(z) or Si_(x) N_(y) film by using the CVD process. InFIG. 48, regions shown by open circles satisfy the conditions in FIGS.14 and 15. That is, FIG. 49 shows the standing wave effect in a case ofusing the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film at 25 nm thickness asan anti-reflective layer and in a case of not using the anti-reflectivelayer. In the case of using the Si_(x) O_(y) N_(z) or Si_(x) N_(y) filmat 25 nm, the standing wave effect was about ±1.8% and the standing waveeffect was reduced to less than about 1/12 as compared with the case ofnot using the anti-reflective layer.

EXAMPLE 54

In this example, a Si_(x) O_(y) N_(z) film having n=2.4±0.6 andk=0.7±0.2 shown in Example 53 was formed by the following method to forman anti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, by using a microwave (2.45 GHz), from a gas mixture of SiH₄ +O₂+N₂ or a gas mixture of SiH₄ +N₂ O.

EXAMPLE 55

In this example, a Si_(x) O_(y) N_(z) film having n=2.4±0.6 andk=0.7±0.2 shown in Example 53 was formed by the following method to forman anti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, by using a microwave (2.45 GHz), from a gas mixture of SiH₄ +O₂+N₂ or a gas mixture of SiH₄ +N₂ O and using Ar as a buffer gas.

EXAMPLE 56

In this example, a Si_(x) O_(y) N_(z) film having n=2.4±0.6 andk=0.7±0.2 shown in Example 53 was formed by the following method to forman anti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +O₂ +N₂ or a gas mixture of SiH₄ +N₂O.

EXAMPLE 57

In this example, a Si_(x) O_(y) N_(z) film having n=2.4±0.6 andk=0.7±0.2 shown in Example 53 was formed by the following method to forman anti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +O₂ +N₂ or a gas mixture of SiH₄ +N₂O and using Ar as a buffer gas.

EXAMPLE 58

In this example, a Si_(x) N_(y) film having n=2.4±0.6 and k=0.7±0.2shown in Example 53 was formed by the following method to form ananti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, by using a microwave (2.45 GHz), from a gas mixture of SiH₄+NH₃ or a gas mixture of SiH₂ Cl₂ +NH₃.

EXAMPLE 59

In this example, an Si_(x) N_(y) film having n=2.4±0.6 and k=0.7±0.2shown in Example 53 was formed by the following method to form ananti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +O₂ or a gas mixture of SiH₂ Cl₂+NH₃ and using Ar as a buffer gas.

EXAMPLE 60

In this example, an Si_(x) N_(y) film having n=2.4±0.6 and k=0.7±0.2shown in Example 53 was formed by the following method to form ananti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, by using a microwave (2.45 GHz), from a gas mixture of SiH₄+NH₃ or a gas mixture of SiH₂ Cl₂ +NH₃.

EXAMPLE 61

In this example, an Si_(x) N_(y) film having n=2.4±0.6 and k=0.7±0.2shown in Example 53 was formed by the following method to form ananti-reflective layer as shown in FIG. 47.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +O₂ or a gas mixture of SiH₂ Cl₂ 30NH₃ by using Ar as a buffer gas.

EXAMPLE 62

In this example, a Si_(x) O_(y) N_(z) or Si_(x) N_(y) film havingn=2.4±0.6 and k=0.7±0.2 shown in Example 53 was etched by the followingmethod using a resist pattern as a mask.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by usinga gas system of CHF₃ (50-100 SCCM)+O₂ (3-20 SCCM), under a pressure ofabout 2 Pa and with a power of about 100-1000 V by using a reactiveetching process with improved ionic property, thereby etching a desiredpattern.

EXAMPLE 63

In this example, a Si_(x) O_(y) N_(z) or Si_(x) N_(y) film havingn=2.4±0.6 and k=0.7±0.2 shown in Example 53 was etched by the followingmethod using a resist pattern as a mask.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by usinga gas system of C₄ F₈ (30-70 SCCM)+CHF₃ (10-30 SCCM), under a pressureof about 2 Pa and with a power of about 100-1000 V by using a reactiveion etching process with improved ionic property, thereby etching adesired pattern.

EXAMPLE 64

In this example, a Si_(x) N_(y) film having n=2.4±0.6 and k=0.7±0.2shown in Example 53 was etched by the following method using a resistpattern as a mask.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by usinga gas system S₂ F₂ (5-30 SCCM), under a pressure of about 2 Pa and witha power of about 100-1000 V by using a reactive etching process withimproved ionic property, thereby etching a desired pattern.

EXAMPLE 65

In this example, the present invention was applied by using a Si_(x)O_(y) N_(z) or Si_(x) N_(y) film as an anti-reflective layer for forminga stable resist pattern on an underlying Al, Al-Si or Al-Si-Cu materialor by way of a silicon oxide film, such as SiO₂, on the underlyingmaterial by using KrF excimer lithography.

In the method of forming the resist pattern in this pattern, as shown inFIG. 50, an anti-reflective layer ARL is formed with Si_(x) O_(y) N_(z)or Si_(x) N_(y) on the underlying Al, Al-Si or Al-Si-Cu material as ametal wiring material, a photoresist PR was formed on theanti-reflective layer ARL or the photoresist PR was formed on theanti-reflective layer after forming a silicon oxide film such as SiO₂ toform a resist pattern. In this example, the present invention wasapplied by using Si_(x) O_(y) N_(z) or Si_(x) N_(y) as theanti-reflective layer ARL, particularly in a case of obtaining a wiringstructure by forming a material layer as wiring with Al, Al-Si orAl-Si-Cu on a substrate, such as a Si semiconductor substrate, orforming a silicon oxide film, such as SiO₂, on the material layer, whichwas then patterned by a photolithographic step using the photoresist PRand an etching step.

At first, description will be made to the procedures for selectingSi_(x) O_(y) N_(z) or Si_(x) N_(y) as the anti-reflective layer to beused on the underlying Al, Al-Si or Al-Si-Cu material and the method ofdetermining the condition to be satisfied by Si_(x) O_(y) N_(z) orSi_(x) N_(y). The following procedures (1)-(6) were conducted.

(1) XP 8843 resist (manufactured by Shipley Microelectronics Co.) wascoated on an Al, Al-Si or Al-Si-Cu substrate without an anti-reflectivelayer and exposed by a KrF excimer laser beam at a wavelength of 248 nm,followed by development. FIG. 20 shows the standing wave effect in thiscase. As shown in FIG. 20, the standing wave effect was about ±29.6%.

(2) In FIG. 20, the maximum value of the standing wave effect situates,for example, at 982 nm of the resist film thickness. FIG. 30 showsequi-contour lines for the amount of absorbed light in the resist filmrelative to the change of optical constants n_(arl), k_(arl) of theanti-reflective layer, wherein the resist film has a thickness of 982nm, and the thickness of the anti-reflective layer is set to 30 nm.

(3) FIGS. 31, 32 and 33 show the results of repeating the procedures (2)above to each of the resist film thicknesses of 1000 nm, 1018 nm and1035 nm, respectively.

(4) As a result of determining a common region in FIG. 30 to FIG. 33,

    n.sub.arl =4.8, k.sub.arl =0.45, or

    n.sub.arl =2.0, k.sub.arl =0.8

were obtained.

That is, the condition to be satisfied by the optimal anti-reflectivelayer with the thickness of the anti-reflective layer being set as 30 nmis:

    n.sub.arl =4.8, k.sub.arl =0.45. or

    n.sub.arl =2.0, k.sub.arl =0.8.

When the standing wave effect was determined by using theabove-mentioned condition, the results shown in FIG. 34 and FIG. 35 wereobtained. In FIG. 34 and FIG. 35, the standing wave effect was extremelysmall and it was about less than ±1% in each of the cases. The standingwave effect was reduced to about 1/60 as compared with the case of notusing the anti-reflective layer.

(5) The procedures (2)-(4) described above were conducted in a case ofsetting the thickness of the anti-reflective layer as 30 nm. When theprocedures (2)-(4) were repeated also for anti-reflective layer (ARLthickness) of other different layer thicknesses, an optimal conditionfor the anti-reflective layer in accordance with the thickness of theanti-reflective layer could be determined. FIG. 14 and FIG. 36 show theobtained results.

(6) It was investigated as to whether the film species capable ofsatisfying the condition to be met by the anti-reflective layerdetermined in (5) above were present or not by using a spectroscopicellipsometer (SOPRA Co.). As a result, it has been found that theoptical constants show the change in FIG. 51 corresponding to thecondition upon forming the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film byusing the CVD process. The region shown by open circles in FIG. 51satisfy the conditions in FIG. 14 and FIG. 36. That is, FIG. 52 showsthe standing wave effect in a case of using the Si_(x) O_(y) N_(z) orSi_(x) N_(y) film at a 25 nm thickness as an anti-reflective layer onthe underlying Al, Al-Si, Al-Si-Cu material and in a case of not usingthe anti-reflective layer. In the case of using the Si_(x) O_(y) N_(z)or Si_(x) N_(y) film at 25 nm, the standing wave effect was about ±0.5%end the standing wave effect was reduced to about 1/60 as compared withthe case of not using the anti-reflective layer.

EXAMPLE 66

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and values on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, using a microwave (2.45 GHz) from a gas mixture of SiH₄ +O₂ +N₂or a gas mixture of SiH₄ +N₂ O.

EXAMPLE 67

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and values on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, using a microwave (2.45 GHz) from e gas mixture of SiH₄ +O₂ +N₂or a gas mixture of SiH₄ +N₂ O and using Ar as a buffer gas.

EXAMPLE 68

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and values on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in the example, a film was formed by utilizing a parallel plateplasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +O₂ +N₂ or a gas mixture of SiH₄ +N₂O.

EXAMPLE 69

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and value on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +O₂ +N₂ or a gas mixture of SiH₄ +N₂O, using Ar as a buffer gas.

EXAMPLE 70

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and values on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, using a microwave (2.45 GHz) from a gas mixture of SiH₄ +NH₃ ora gas mixture of SiH₂ Cl₂ +NH₃.

EXAMPLE 71

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and values on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, using a microwave (2.45 GHz) from a gas mixture of SiH₄ +O₂ ora gas mixture of SiH₂ Cl₂ +NH₃ using Ar as a buffer gas.

EXAMPLE 72

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and values on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +NH₃ or a gas mixture of SiH₂ Cl₂+NH₃.

EXAMPLE 73

In this example, an Si_(x) O_(y) N_(z) film within a range of values onthe curve in the graph showing the relation between the thickness of theanti-reflective layer and the optical property to be satisfied by theoptimum anti-reflective layer (FIG. 14, FIG. 36) or values on the curve±0.3 for n and values on the curve ±0.3 for k shown in Example 65 wasformed by the method described below to form an anti-reflective layershown in FIG. 50.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess, from a gas mixture of SiH₄ +O₂ or a gas mixture of SiH₂ Cl₂+NH₃ using Ar as a buffer gas.

EXAMPLE 74

In this example, a Si_(x) O_(y) N_(z) or Si_(x) N_(y) film within arange of values on the curve in the Figure (FIG. 14, FIG. 36) showing arelationship between the thickness of the anti-reflective layer and theoptical property to be satisfied by the optimum anti-reflective layer orvalues on the curve ±0.3 for n and values on the curve ±0.3 for k wasetched by the following method using the resist pattern as a mask forthe underlying material.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by areactive etching process using a gas system of CHF₃ (50-100 SCCM)+O₂(3-20 SCCM) under a pressure of about 2 Pa and with a power of about 100to 1000 W and improved with the ionic property to etch a desiredpattern.

EXAMPLE 75

In this example, a Si_(x) O_(y) N_(z) or Si_(x) N_(y) film within arange of values on the curve in the Figure (FIG. 14, FIG. 36) showing arelationship between the thickness of the anti-reflective layer and theoptical property to be satisfied by the optimum anti-reflective layer orvalues on the curve ±0.3 for n and values on the curve ±0.3 for k wasetched by the following method using the resist pattern as a mask forthe underlying material.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by areactive etching process using a gas system of C₄ F₈ (30-70 SCCM)+CHF₃(10-30 SCCM) under a pressure of about 2 Pa and with a power of about100 to 1000 W and improved with the ionic property to etch a desiredpattern.

EXAMPLE 76

In this example, a Si_(x) O_(y) N_(z) or Si_(x) N_(y) film within arange of values on the curve in the Figure (FIG. 14, FIG. 36) showing arelationship between the thickness of the anti-reflective layer and theoptical property to be satisfied by the optimum anti-reflective layer orvalues on the curve ±0.3 for n and values on the curve ±0.3 for k wasetched by the following method using the resist pattern as a mask forthe underlying material.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by areactive etching process using ages system of S₂ F₂ (5-30 SCCM) under apressure of about 2 Pa and with a power of about 100 to 1000 W andimproved with the ionic property to etch a desired pattern.

EXAMPLE 77

In this example, in a case of forming a stable resist pattern on asilicon substrate, such as of single crystal silicon, polycrystallinesilicon, amorphous silicon or doped polysilicon and, by way of a siliconoxide film, such as SiO₂, on the underlying material by using a KrFexcimer laser, it has been found according to the present invention thatuse of an organic or inorganic film having n=1.8-2.6 and k=0.1-0.8,particularly a Si_(x) O_(y) N_(z) or Si_(x) N_(y) film at a filmthickness of 20-150 nm as the anti-reflective layer was desirable.

In a case of using the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film as theanti-reflective layer, the film could be formed by various types of CVDprocesses. Further, Si_(x) O_(y) N_(z) or Si_(x) N_(y) could be etchedby RIE using CHF₃, C₄ F₈, CHF₃ S₂ F₂ series gas as an etchant andimproved with the ionic property.

That is, in this example, the present invention was applied in a case ofusing the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film as the anti-reflectivelayer for forming a stable resist pattern on a silicon series substrate,such as single crystal silicon and, by way of a silicon oxide film, suchas SiO₂, on the above-mentioned substrate by using KrF excimerlithography.

As shown in FIG. 53, in the method of forming a resist pattern in thisexample, an anti-reflective layer ARL was formed with Si_(x) O_(y) N_(z)or Si_(x) N_(y) on a silicon series substrate G, such as single crystalsilicon, a photoresist PR was formed on the anti-reflective layer ARL,or the photoresist PR was formed after forming the silicon oxide film Oxsuch as SiO₂ on the anti-reflective layer, thereby forming a resistpattern.

In this example, the present invention was applied, particularly in acase of forming a silicon oxide film Ox, such as SiO₂, on a siliconseries substrate G, such as of single crystal silicon or on the materiallayer, which was patterned by a photolithographic step using thephotoresist PR and an etching step, in which Si_(x) O_(y) N_(z) orSi_(x) N_(y) was used as the anti-reflective layer ARL.

At first, description will be made to procedures for selecting anorganic or inorganic film, particularly, a Si_(x) O_(y) N_(z) or Si_(x)N_(y) film having n=1.8-2.6 and k=0.1-0.8 at a film thickness=20-150 nmas an anti-reflective layer on the silicon series substrate G such as ofsingle crystal silicon or on the underlying material, as well as amethod of determining the condition to be satisfied therewith. Thefollowing procedures (1)-(6) were conducted.

(1) XP 8843 resist (manufactured by Shipley Microelectronics Co.) wascoated on a Si series substrate without an anti-reflective layer andexposed by a KrF excimer laser beam at a wavelength of 248 nm, followedby development. FIG. 41 shows the standing wave effect in this case. Asshown in FIG. 41, the standing wave effect was about ±20%.

(2) In FIG. 41, the maximum value of the standing wave effect situates,for example, at 985 nm of the resist film thickness. Fluctuation for theamount of absorbed light in the resist film was determined relative tothe change of optical constants n_(arl), k_(arl) Of the anti-reflectivelayer, taking notice on the resist film thickness of 982 nm, and settingthe thickness of the anti-reflective layer to 30 nm.

(3) The procedure (2) was repeated for each of a plurality of resistfilms of different thicknesses.

(4) The results are shown in the Figures and a common region in them wasdetermined. Such a procedure was determined for each kind of the filmthicknesses of the anti-reflective layers, by which an optimum value (nvalue, k value) of the optical property of a certain film thickness wasdetermined. For instance, the optimum condition to be satisfied by theoptimum anti-reflective layer in a case of setting the thickness of theanti-reflective layer as 32 nm was:

    n.sub.arl =2.0, k.sub.arl =0.55.

Further, the optical condition to be satisfied by the optimumanti-reflective layer upon setting the thickness of the anti-reflectivelayer as 100 nm was:

    n.sub.arl =1.9, k.sub.arl =0.35.

When the standing wave effect was determined by using theabove-mentioned two conditions, results as shown in FIGS. 54 and 55 wereobtained. In FIGS. 54 and 55, the standing wave effect shown at theoptimum value was extremely small and it was less than about ±1% in eachof the cases. The standing wave effect was reduced to less than about1/20 as compared with the case of not using the anti-reflective layer.

(5) The procedures (2)-(4) described above were applied to a case ofsetting the thickness of the anti-reflective layer as 32 nm and 100 nm.When the procedures (2)-(4) were repeated also to other differentthicknesses of the anti-reflective layer (ARL layer thickness), anoptimum condition for the anti-reflective layer depending on thethickness of the anti-reflective layer could be determined.

(6) It was investigated as to whether film species capable of satisfyingthe condition to be met by the anti-reflective layer determined in (5)above were present or not by using a spectroscopic ellipsometer (SOPRACo.). As a result, it has been found that the optical constants show thechange in FIG. 56 corresponding to the condition upon forming the Si_(x)O_(y) N_(z) or Si_(x) N_(y) film by using the CVD process. The regionsshown by open circles in FIG. 56 satisfy the conditions for (4)described above. FIGS. 54 and 55 show the results determining thestanding wave effect under the condition shown by the open circles inFIG. 56. In each of the cases, the standing wave effect was less thanabout ±1.0% by using the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film as theanti-reflective layer and the standing wave effect was reduced to about1/20 as compared with the case of not using the anti-reflective layer.

EXAMPLE 78

In this example, Si_(x) O_(y) N_(z) or Si_(x) N_(y) was used as theanti-reflective layer ARL, particularly, in a case of patterning asilicon oxide film, such as SiO₂, on a silicon series substrate such asof polycrystalline silicon, amorphous silicon or doped polysilicon, oron the material layer by a photolithographic step using a photoresist PRand an etching step by using the method shown in Example 77.

At first, description will be made to the procedures for selecting anorganic or inorganic film having n=1.8-2.6 and k=0.2-0.8 at a filmthickness of 20-150 nm, in particular, a Si_(x) O_(y) N_(z) or Si_(x)N_(y) film as an anti-reflective layer on a silicon series substrate,such as of polycrystalline silicon, amorphous silicon or dopedpolysilicon by using the same method as in Example 77, as well as amethod of determining the condition to be satisfied therewith.

(1) The optical condition to be satisfied by the optimum anti-reflectivelayer with a thickness of the anti-reflective layer, for example, of 33nm by using the same method as in Example 77 was n_(arl) =2.01, k_(arl)=0.62. When the standing wave effect was determined by using thiscondition, the result, as shown in FIG. 57, was obtained. The standingeffect in FIG. 57 was extremely small and it was about less than ±1% ineach of the cases. The standing wave effect was reduced to about 1/20 ascompared with the case of not using the anti-reflective layer.

(2) The foregoing procedures were applied to the case of setting thethickness of the anti-reflective layer to 33 nm. When theabove-mentioned procedures were repeated also for other anti-reflectivelayers of different thicknesses (ARL layer thickness), an optimumcondition for the anti-reflective layer in accordance with the thicknessof the anti-reflective layer was obtained.

(3) The condition to be satisfied by the anti-reflective layerdetermined above corresponds to the region shown by open circles in thechange of the optical constants corresponding to the condition uponforming the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film by using the CVDprocess (refer to FIG. 56). FIG. 57 shows the standing wave effect inthe case of using the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film at athickness of 33 nm as the anti-reflective layer on the silicon seriessubstrate, such as of polycrystalline silicon, amorphous silicon anddoped polysilicon and in a case of not using the anti-reflective layer.The standing wave effect in a case of setting the thickness of theSi_(x) O_(y) N_(z) or Si_(x) N_(y) film to 33 nm was less than about±1.0% and the standing wave effect was reduced to less than about 1/20as compared with the case of not using the anti-reflective layer.

EXAMPLE 79

In this example, the Si_(x) O_(y) N_(z) film shown in Examples 77 and 78was formed by the following method to form an anti-reflective layer asshown in Example 53.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess using a microwave (2.45 GHz) for a gas mixture of SiH₄ +O₂ +N₂or a gas mixture of SiH₄ +N₂ O.

EXAMPLE 80

In this example, the Si_(x) O_(y) N_(z) film shown in Examples 77 and 78was formed by the following method to form the anti-reflective layer asshown in FIG. 53.

That is, in this example, the film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or bias ECR plasma CVDprocess at a microwave (2.45 GHz) from a gas mixture of SiH₄ +O₂ +N₂ ora gas mixture of SiH₄ +N₂ O using Ar as a buffer gas.

EXAMPLE 81

In this example, the Si_(x) O_(y) N_(z) film shown in Examples 77 and 78was formed by the following method to form the anti-reflective layer asshown in FIG. 53.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or a bias ECR plasmaCVD process from a gas mixture of SiH₄ +O₂ +N₂ or a gas mixture of SiH₄+N₂ O.

EXAMPLE 82

In this example, the Si_(x) O_(y) N_(z) film shown in Examples 77 and 78was formed by the following method to form the anti-reflective layer asshown in FIG. 53.

That is, in this example, a film formed by utilizing a parallel plateplasma CVD process, ECR plasma CVD process or a bias ECR plasma CVDprocess from a gas mixture of SiH₄ +O₂ +N₂ or a gas mixture of SiH₄ +N₂O and using Ar as a buffer gas.

EXAMPLE 83

In this example, the Si_(x) N_(y) film shown in Examples 77 and 78 wasformed by the following method to form the anti-reflective layer asshown in FIG. 53.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or a bias ECR plasmaCVD process using a microwave (2.45 GHz) from a gas mixture of SiH₄ +NH₃or a gas mixture of SiH₂ Cl₂ +NH₃.

EXAMPLE 84

In this example, the Si_(x) N_(y) film shown in Examples 77 and 78 wasformed by the following method to form the anti-reflective layer asshown in FIG. 53.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or a bias ECR plasmaCVD process using a microwave (2.45 GHz) from a gas mixture of SiH₄ +O₂or a gas mixture of SiH₂ Cl₂ +NH₃ using Ar as a buffer gas.

EXAMPLE 85

In this example, the Si_(x) N_(y) film shown in Examples 77 and 78 wasformed by the following method to form the anti-reflective layer asshown in FIG. 53.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or a bias ECR plasmaCVD process from a gas mixture of SiH₄ +N₃ or a gas mixture of SiH₂ Cl₂+NH₃.

EXAMPLE 86

In this example, the Si_(x) N_(y) film shown in Examples 77 and 78 wasformed by the following method to form the anti-reflective layer asshown in FIG. 53.

That is, in this example, a film was formed by utilizing a parallelplate plasma CVD process, ECR plasma CVD process or a bias ECR plasmaCVD process from a gas mixture of SiH₄ +O₂ or a gas mixture of SiH₂ Cl₂+NH₃ using Ar as a buffer gas.

EXAMPLE 87

In this example, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film shown inExamples 77 and 78 was etched as the underlying material using theresist pattern as a mask by the following method.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by areactive etching process using a gas system of CHF₃ (50-100 SCCM)+O₂(3-20 SCCM), under a pressure of about 2 Pa, with a power of about10-1000 W and with the improved ionic property, to obtain a desiredpattern by etching.

EXAMPLE 88

In this example, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film shown inExamples 77 and 78 was etched as the underlying material using theresist pattern as a mask by the following method.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by areactive etching process using a gas system of C₄ F₈ (30-70 SCCM)+CHF₃(10-30 SCCM), under a pressure of about 2 Pa, with a power of about100-1000 W and with the improved ionic property, to obtain a desiredpattern by etching.

EXAMPLE 89

In this example, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film shown inExamples 77 and 78 was etched as the underlying material using theresist pattern as a mask by the following method.

That is, the Si_(x) O_(y) N_(z) or Si_(x) N_(y) film was etched by areactive etching process using a gas system of S₂ F₂ (5-30 SCCM), undera pressure of about 2 Pa, with a power of about 100-1000 W and with theimproved ionic property, to obtain a desired pattern by etching.

EXAMPLE 90

In this example, a SiO_(x) N_(y) film is formed by using SiH₄ and N₂ Omix gas as raw gas. It is recognized that the formed film containshydrogen.

Referring to FIG. 58 and FIG. 59, FIG. 58 shows relationship betweencurrent ratio SiH₄ /N₂ O and n, k value of the formed film in thisexample. FIG. 59 shows relationship between current ratio SiH₄ /N₂ O andatomic ratio of Si, O, N, H (atom %) of the formed film in this example.As is understood through FIG. 59, the formed SiO_(x) N_(y) film containsH with ratio of H changing in accordance to the current ratio SiH₄ /N₂O. It shows the fact that SiO_(x) N_(y) H_(z) film is formed.

Qualitatively speaking, as appeared in IR spectrum in FIG. 60, in anycase of various current ratio, there exists not only peaks showing Si-Oor Si-N bond but exists peaks showing N-H, Si-H bond.

It is considered that the existence of the hydrogen makes a contributionto the anti-reflective effect to e certain extent. It is considered thatthere exists hydrogen in any shape in the obtained film, whenhydrogen-containing raw gas is used. Especially, in film forming methodusing plasma, the existence of such hydrogen is remarkable.

In this example, various x, y, z values of SiO_(x) N_(y) H_(z) filminvestigated from the current ratio SiH₄ /N₂ O based on FIG. 58 whichgives most suitable k and n values for an i-line and excimer laser areshown in following Table 1. In this experiment, WSi as refractory metalsilicide WSi with SiO₂, and Al-1 wt % Si as metal material are used asunderlying material. And on the above-mentioned underlying materials,various thicknesses of anti-reflective layers are formed on saidunderlying material using said SiH₄ /N₂ O mixed gas.

                  TABLE 1                                                         ______________________________________                                        x · y · z values of SiO.sub.x N.sub.y H.sub.z                                      thick-                                                                        ness                                                                          of anti-                                                                      reflec-              current                                underlying        tive lay-            ratio of                          No.  material  light   er (nm)                                                                             x    y    z    SiH.sub.4 /N.sub.2 O              ______________________________________                                        1    WSi       i-      27    0.614                                                                              0.227                                                                              0.432                                                                              1.0                                              line                                                           2    WSi       excimer 30    0.479                                                                              0.208                                                                              0.375                                                                              1.43                                   (with SiO.sub.2)                                                         3    Al--Si    excimer 24    0.358                                                                              0.189                                                                              0.358                                                                              1.85                              4    Al--Si    excimer 70    0.842                                                                              0.263                                                                              0.526                                                                              0.66                              ______________________________________                                    

Points of current ratio corresponding to the above 1 to 4, there aredrawn the lines showing them, in FIG. 59.

According to the present invention, the following are understood. Incase that SiO_(x) N_(y) H_(z) is used as an anti-reflective layer toform WSi for wavelength 150 to 450 nm, it is preferred that x is 0.03 to0.80, y is 0.10 to 0.30, sad z can be zero, but when hydrogen iscontained, it is preferred that z is 0.20 to 0.60.

According to the present invention, the following are also understood.In case that SiO_(x) N_(y) :H_(z) is used as an anti-reflective layerfor Al-Si for wavelength 150 to 450 nm, it is preferred that x is 0.03to 0.70 and y is 0.05 to 0.30. z can be zero, but when hydrogen iscontained, it is preferred that z is 0.1 to 0.5.

As shown in FIG. 61, ordinarily used current ratio of SiH₄ /N₂ O forforming SiO_(x) N_(y) film is 0.2 to 2.0.

FIGS. 62 and 63 show simulated anti-reflect effect (effect fordecreasing standing wave) when anti-reflective layers obtained in thisexample are used. FIG. 62 shows the case that WSi with SiO₂ is used asunderlying material. FIG. 63 shows the case that Al-Si is used asunderlying material. By referring to FIGS. 62 and 63, it is understoodthat in the case having anti-reflective layers (with ARL) therediminished most of the standing effect, compared with the case having noanti-reflective layers (without ARL).

FIG. 64 shows the measured anti-reflect effect on 0.44 m line and spacepattern in real i-line lithography process. By referring to FIG. 64,anti-reflect effect in this example is also understood.

FIGS. 65 and 66 show simulated anti-reflect effect. FIG. 65 shows thecase that WSi is used as underlying material (i-line, absorption ratio).FIG. 66 shows also the case that WSi is used as underlying material(i-line, reflective ratio). An anti-reflective layer of 30 nm with n, kvalue described in the Figures is formed, and data are measured by usingphotoresist with n, k value described in the Figure. Superioranti-reflective effect is obtained in both cases of absorption ratio andreflective ratio.

FIGS. 67 and 68 show the relationship between thickness of photoresistand critical dimension. The experiment is operated using WSi asunderlying material, and KrF excimer laser. FIG. 67 shows the case thatdata are measured concerning 0.30 m line and space pattern. FIG. 68shows the case that data are measured concerning 0.35 m line and spacepattern. In both cases, chemical amplifying positive resist is used.

EXAMPLE 91

As aforementioned, the material n value of which is about 2.4 and kvalue of which is about 0.7 is suitable as an anti-reflective layer forexcimer laser on, for example, refractory metal silicide. And also asaforementioned, SiO_(x), SiN_(x) or SiO_(x) N_(y) is effective such ananti-reflective layer as described above. It is considered that SiO_(x),SiN_(x) or SiO_(x) N_(y) with the n value and k value as described abovewhich is effective for anti-reflectivity can be formed by controllingthe n value and k value by controlling the element ratio x and y. It is,however, difficult to obtain a film with desired n value and k value bycontrolling the ratio by suitable means.

In this example, in order to obtain a film with desired n value and kvalue, the anti-reflective layer is formed by using a raw gas containingat least silicon element and oxide element. For example, in order tocontrol the element ratio x of SiO_(x), by using gas current ratio asparameter, it is possible to make x smaller through using higher ratioof raw gas containing silicon element. As a result, the atomic ratio canbe controlled, and the optical constant (n, k) can be controlled.

In this example, SiH₄ is used as raw gas containing at least siliconelement, and N₂ O is sued as raw gas containing at least oxide element.The film with desired anti-reflective effect can be formed bycontrolling the optical constant through using current ratio of SiH₄ andN₂ O as parameter. FIG. 58 shows the change of the optical constant ofthe formed film when the current ratio of SiH₄ and N₂ O in parallelelectrode-type plasma CVD chamber is changed. The suitable example offilm forming conditions for excimer lithography are as follows:

    SiH.sub.4 =50 sccm

    N.sub.2 O=50 sccm

    RF power=190 W

    pressure=332.5 Pa (2.5 torr)

    temperature of the substrate=400° C.

    distance between electrodes=1 cm.

In the above-mentioned means, current ratio of raw gas is mainly used asto control optical constant, however, pressure of film formingatmosphere, RF power, or temperature of the substrate can be used tocontrol optical constant as parameter.

EXAMPLE 92

In this example, an anti-reflective layer is formed by using at leastone kind of organic compounds containing at least silicon element as araw material. As a result of using an organic compound, coverage of ananti-reflective layer on a step improves. Namely, a difference betweenthickness of an anti-reflective layer on even portion and that ofperpendicular portion of a step in this example is small, and uniformityof anti-reflective effect in semiconductor device tip improves.

In this example, as an organic compound which has improved step coverageis used, this example can be said it is especially effective for devicewith severe unevenness. As an organic compound, for example, TEOS, OMCTS(Si₄ O(CH₃)₈ :Si/Uratio=1). HMDS (Si₂ O(CH₃)₈ :Si/Oratio=2) and so oncan be used. In this example, used conditions for forming film inparallel electrodes plasma CVD chamber are as follows:

    OMCTS=50 sccm

    RF power=190 W

    pressure=332.5 Pa (2.5 torr)

    temperature of the substrate=400° C.

    distance between electrodes=1 cm.

EXAMPLE 93

When Si content of the desired film is larger than the above Example 92,SiH₄, which is a Si source gas without containing O, N, can be added. Inthis case, the example of conditions for forming the film in parallelelectrode plasma CVD chamber are as follows:

    OMCTS=50 sccm

    SiH.sub.4 =5 sccm

    RF power=190 W

    pressure=332.50 Pa (2.5 torr)

    temperature of the substrate=400° C.

    distance between electrodes-1 cm.

As has been described above, according to the present invention, in acase of forming a resist pattern on an optional underlying material(substrate) by using an optional monochromatic light as an exposureoptical source, the condition for an anti-reflective layer used thereincan be determined such that a stable resist pattern can be formedsatisfactorily even if the resist pattern is fine. Further, according tothe present invention, an anti-reflective layer with such a conditioncan be formed. Furthermore, according to the present invention, ananti-reflective layer with such a condition can be formed. Furthermore,according to the present invention, a novel anti-reflective layer can bedeveloped to provide a method of forming a resist pattern using such ananti-reflective layer.

Although various minor modifications may be suggested by those versed inthe art, it should be understood that we wish to embody within the scopeof the patent granted hereon all such modifications as reasonably andproperly come within the scope of our contribution to the art.

We claim:
 1. A method of forming a photoresist pattern, said method comprising the steps of:forming a first layer; forming an anti-reflective layer of an inorganic material composed of Si, O and N on the first layer; forming a photoresist layer on said anti-reflective layer; exposing said photoresist layer selectivity by a monochromatic light to form exposed and non-exposed imagewise areas; and developing said photoresist layer after said exposing to remove some of the imagewise areas of the photoresist layer to uncover portions of the anti-reflective layer, wherein said anti-reflective layer is formed to minimize standing wave effect in said photoresist layer.
 2. A method of forming a photoresist pattern according to claim 1, which includes performing a step of forming a second layer between the steps of forming the anti-reflective layer and forming the photoresist layer.
 3. A method of forming a photoresist pattern according to claim 1, wherein said monochromatic light has a wavelength 150-450nm, and said anti-reflective layer has a reflection refractive index n, an absorption refractive index k and a thickness d, wherein 1.2<n<5.7; 0<k<1.4; and 10 nm<d<100nm.
 4. A method of forming a photoresist pattern according to claim 1, wherein said monochromatic light has a wavelength 150-450nm, and said anti-reflective layer has a reflection refractive index n, an absorption refractive index k and a thickness d, wherein 1.2<n<3.4; 0.16<k<0.72; and 10 nm<d<100 nm.
 5. A method of forming a photoresist pattern according to claim 4, wherein said first layer is selected from a group consisting of a refractory metal layer and a refractory metal silicide layer.
 6. A method of forming a photoresist pattern according to claim 1, wherein said monochromatic light has a wavelength 150-450nm, and said anti-reflective layer has a reflection refractive index n, an absorption refractive index k and a thickness d, wherein 1.9<n<5.7; 0<k<0.46; and 25 nm<d<100 nm.
 7. A method for forming a photoresist pattern according to claim 6, wherein said first layer is selected from a group consisting of a refractory metal layer and a refractory metal silicide layer.
 8. A method of forming a photoresist pattern according to claim 1, wherein said monochromatic light has a wavelength 150-450nm, and said anti-reflective layer has a reflection refractive index n, an absorption refractive index k and a thickness d, wherein 1.2<n<3.4; 0.4<k<1.4; and 10 nm<d<100 nm.
 9. A method of forming a photoresist pattern according to claim 8, wherein said first layer is selected from a group consisting of a metal layer, a metal silicide layer and a metal alloy layer.
 10. A method of forming a photoresist pattern according to claim 1, wherein said monochromatic light has a wavelength 150-450nm, and said anti-reflective layer has a reflection refractive index n, an absorption refractive index k and a thickness d, wherein 1.9<n<5.7; 0.2<k<0.62; and 25 nm<d<100 nm.
 11. A method of forming a photoresist pattern according to claim 10, wherein said first layer is selected from a group consisting of a metal layer, a metal silicide layer and metal alloy layer.
 12. A method of forming a photoresist pattern according to claim 1, wherein said anti-reflective layer has a composition of SiO_(x) N_(y) H_(z), wherein x is 0.3 to 1.30, y is 0.09 to 0.35 and z is 0 to 0.85. 